The great disciple of Plato was Aristotle, and he carried on the philosophical movement which Socrates had started to the highest limit that it ever reached in the ancient world. He was born at Stagira B.C. 384, of wealthy parents, and early evinced an insatiable thirst for knowledge. When Plato returned from Sicily he joined his disciples, and was his pupil for seventeen years, at Athens. On the death of Plato, he went on his travels, and became the tutor of Alexander the Great, and B.C. 335, returned to Athens, after an absence of twelve years, and set up a school, and taught in the Lyceum. He taught while walking up and down the shady walks which surrounded it, from which he obtained the name of Peripatetic, which has clung to his name and philosophy. His school had a great celebrity, and from it proceeded illustrious philosophers, statesmen, historians, and orators. He taught thirteen years, during which he composed most of his greater works. He not only wrote on dialectics and logic, but also on physics in its various departments. His work on "The History of Animals" was deemed so important that his royal pupil presented him with eight hundred talents— an enormous sum—for the collection of materials. He also wrote on ethics and politics, history and rhetoric; letters, poems, and speeches, three fourths of which are lost. He was one of the most voluminous writers of antiquity, and probably the most learned man whose writings have come down to us. Nor has any one of the ancients exercised upon the thinking of succeeding ages so great an influence. He was an oracle until the revival of learning.
[Sidenote: Genius of Aristotle.]
"Aristotle," says Hegel, "penetrated into the whole mass, and into every department of the universe of things, and subjected to the comprehension its scattered wealth; and the greater number of the philosophical sciences owe to him their separation and commencement." [Footnote: Hagel is said to have comprehended Aristotle better than any modern writer, and the best work on his philosophy is by him.] He is also the father of the history of philosophy, since he gives an historical review of the way in which the subject has been hitherto treated by the earlier philosophers.
"Plato made the external world the region of the incomplete and bad, of the contradictory and the false, and recognized absolute truth only in the eternal immutable ideas. Aristotle laid down the proposition that the idea, which cannot of itself fashion itself into reality, is powerless, and has only a potential existence, and that it becomes a living reality, only by realizing itself in a creative manner by means of its own energy." [Footnote: Adolph Stahr, Oldenburg.]
[Sidenote: Vast attainments of Aristotle.]
But there can be no doubt as to his marvelous power of systematization. Collecting together all the results of ancient speculation, he so elaborated them into a coordinate system, that for two thousand years he reigned supreme in the schools. In a literary point of view, Plato was doubtless his superior, but Plato was a poet making philosophy divine and musical; but Aristotle's investigations spread over a far wider range. He wrote also on politics, natural history, and ethics, in so comprehensive and able manner, as to prove his claim to be one of the greatest intellects of antiquity, the most subtle and the most patient. He differed from Plato chiefly in relation to the doctrine of ideas, without however resolving the difficulty which divided them. As he made matter to be the eternal ground of phenomena, he reduced the notion of it to a precision it never before enjoyed, and established thereby a necessary element in human science. But being bound to matter, he did not soar, as Plato did, into the higher regions of speculation; nor did he entertain as lofty views of God, or of immortality. Neither did he have as high an ideal of human life. His definition of the highest good was a perfect practical activity in a perfect life.
With Aristotle closed the great Socratic movement in the history of speculation. When Socrates appeared there was the general prevalence of skepticism, arising from the unsatisfactory speculations respecting nature. He removed this skepticism by inventing a new method, and by withdrawing the mind from the contemplation of nature, to the study of man himself. He bade men to look inward.
[Sidenote: Ethics the great subject of inquiry with Plato.]
Plato accepted his method, but applied it more universally. Like Socrates, however, ethics were the great subject of his inquiries, to which physics were only subordinate. The problem he sought to solve was the way to live like the gods. He would contemplate truth as the great aim of life.
[Sidenote: Main inquiries of Aristotle had reference to physics and metaphysics.]
With Aristotle, ethics formed only one branch of his attention. His main inquiries were in reference to physics and metaphysics. He thus, by bringing these into the region or inquiry, paved the way for a new epoch of skepticism. [Footnote: Lewes, Ritter, Hegel, Maurice, Diogenes Laertius. See fine article inEncyclopedia Britannica.Schwegler, translated by Seelyn.]
It is impossible, within the proper limits of this chapter, to enter upon an analysis of the philosophy of either the three great lights of the ancient world, or to enumerate and describe their other writings. I merely wish to show what are considered to be the vital principles on which their systems were based, and the general spirit of their speculations. The student must examine these in the elaborate treatises of modern philosophers, and in the original works of Plato and Aristotle.
[Sidenote: Their characteristic inquiries.]
Both Plato and Aristotle taught that reason alone could form science; but Aristotle differed from his master respecting the theory of ideas. He did not deny to ideas asubjectiveexistence, but he did deny that they have an objective existence. And he maintained that the individual things aloneexisted, and if individuals only exist, they can only be known bysensation. Sensation thus becomes the basis of knowledge. Plato made reason the basis of knowledge, but Aristotle madeexperience. Plato directed man to the contemplation of ideas; Aristotle, to the observations of Nature. Instead of proceeding synthetically and dialectically like Plato, he pursues an analytic course. His method is hence inductive—the derivation of certain principles from a sum of given facts and phenomena. It would seem that positive science commenced with him, since he maintained that experience furnishes the principles of every science; but, while his conception was just, there was not sufficient experience then accumulated from which to generalize with effect. He did not sufficiently verify his premises. His reasoning was correct upon the data given, as in the famous syllogism, "All black birds are crows; this bird is black; therefore this bird is a crow." The defect of the syllogism is not in the reasoning, but in the truth of the major premise, since all black birds are not crows. It is only a most extensive and exhaustive examination of the accuracy of a proposition which will warrant reasoning upon it. Aristotle reasoned without sufficient examination of the major premise of his syllogisms.
[Sidenote: Logic of Aristotle.]
Aristotle was the father of logic, and Hegel and Kant think there has been no improvement upon it since his day. And this became to him the real organon of science. "He supposed it was not merely the instrument of thought, but the instrument of investigation." Hence it was futile for purposes of discovery, although important to aid the processes of thought. Induction and syllogism are the two great instruments of his logic. The one sets out from particulars already known to arrive at a conclusion; the other sets out from some general principle to arrive at particulars. The latter more particularly characterized his logic, which he presented in sixteen forms, showing great ingenuity, and useful as a dialectical exercise. This syllogistic process of reasoning would be incontrovertible, if thegeneralwere better known than theparticular. But it is only by induction, which proceeds from the world of experience, that we reach the higher world of cognition. We arrive at no new knowledge by the syllogism, since the major premise is more evident than the conclusion, and anterior to it. Thus he made speculation subordinate to logical distinctions, and his system, when carried out by the schoolmen, led to a spirit of useless quibbling. Instead of interrogating Nature, as Bacon led the way, they interrogated their own minds, and no great discoveries were made. From a want of a proper knowledge of the conditions of scientific inquiry, the method of Aristotle became fruitless. [Footnote: Maurice,Anc. Phil. See Whewell,Hist. Ind. Science.]
Though Aristotle wrote in a methodical manner, yet there is great parsimony of language. There is no fascination in his style. It is without ornament, and very condensed. His merit consisted in great logical precision, and scrupulous exactness in the employment of terms.
[Sidenote: The Skeptics.]
Philosophy, as a great system of dialectics, as an analysis of the power and faculties of the mind, as a method to pursue inquiries, as an intellectual system merely, culminated in Aristotle. He completed the great fabric of which Thales laid the foundation. The subsequent schools of philosophy directed attention to ethical and practical questions, rather than to intellectual phenomena. The skeptics, like Pyrrho, had only negative doctrines, and had a disdain of those inquiries which sought to penetrate the mysteries of existence. They did not believe that absolute truth was attainable by man. And they attacked the prevailing systems with great plausibility. Thus Sextus attacked both induction and definitions. "If we do not know the thing we define," said he, "we do not comprehend it because of the definition, but we impose on it the definition because we know it; and if we are ignorant of the thing we would define, it is impossible to define it." Thus the skeptics pointed out the uncertainty of things and the folly of striving to comprehend them.
The Epicureans despised the investigations of philosophy, since, in their view, they did not contribute to happiness. The subject of their inquiries was happiness, not truth. What will promote this, was the subject of their speculation. Epicurus, born B.C. 342, contended that pleasure was happiness; that pleasure should not be sought for its own sake, but with a view of the happiness of life obtained by it. He taught that it was inseparable from virtue, and that its enjoyments should be limited. He was averse to costly pleasures, and regarded contentedness with a little to be a great good. He placed wealth not in great possessions, but few wants. He sought to widen the domain of pleasure, and narrow that of pain, and regarded a passionless state of life the highest. Nor did he dread death, which was deliverance from misery. Epicurus has been much misunderstood, and his doctrines were subsequently perverted, especially when the arts of life were brought into the service of luxury, and a gross materialism was the great feature of society. Epicurus had much of the practical spirit of a philosopher, although very little of the earnest cravings of a religious man. He himself led a virtuous life, because it was wiser and better to be virtuous, not because it was his duty. His writings were very voluminous, and in his tranquil garden he led a peaceful life of study and enjoyment. His followers, and they were numerous, were led into luxury and effeminacy, as was to be expected from a skeptical and irreligious philosophy, the great principle of which was that whatever is pleasant should be the object of existence. [Footnote: the doctrines of the Epicureans are best set forth in Lucretius.]
The Stoics were a large and celebrated sect of philosophers; but they added nothing to the domain of thought,—they created no system, they invented no new method, they were led into no new psychological inquiries. Their inquiries were chiefly ethical. And if ethics are a part of the great system of Grecian philosophy, they are well worthy of attention. Some of the greatest men of antiquity are numbered among them—like Seneca and Marcus Aurelius. The philosophy they taught was morality, and this was eminently practical and also elevated.
[Sidenote: Zeno.]
The founder of this sect, Zeno, born rich, but reduced to poverty by misfortune, was a very remarkable man, and a very good one, and profoundly revered by the Athenians, who intrusted him with the keys of their citadel. The date of his birth is unknown, but he lived in a degenerate age, when skepticism and sensuality were eating out the life and vigor of Grecian society, when Greek civilization was rapidly passing away, when ancient creeds had lost their majesty, and general levity and folly overspread the land. Deeply impressed with the prevailing laxity of morals and the absence of religion, he lifted up his voice, more as a reformer than as an inquirer after truth, and taught for more than fifty years in a place called the Porch, which had once been the resort of the poets. He was chiefly absorbed with ethical questions, although he studied profoundly the systems of the old philosophers. He combated Plato's doctrine that virtue consists in contemplation, and of Epicurus, that it consisted in pleasure. Man, in his eyes, was made for active duties. He also sought to oppose skepticism, which was casting the funereal veil of doubt and uncertainty over every thing pertaining to the soul, and God, and the future life. "The skeptics had attacked both perception and reason. They had shown that perception is, after all, based upon appearance, and appearance is not a certainty; and they showed that reason is unable to distinguish between appearance and certainty, since it had nothing but phenomena to build upon, and since there is no criterion to apply to reason itself." Then they proclaimed philosophy a failure, and without foundation. But he, taking a stand on common sense, fought for morality, as did Reid and Beattie, when they combated the skepticism of Hume.
[Sidenote: Doctrines of the Stoics.]
[Sidenote: Influence of the Stoics.]
Philosophy, according to Zeno and other Stoics, was intimately connected with the duties of practical life. The contemplation, recommended by Plato and Aristotle, seemed only a covert recommendation of selfish enjoyment. The wisdom, which it should be the aim of life to attain, is virtue. And virtue is to live harmoniously with nature. To live harmoniously with nature is to exclude all personal ends. Hence pleasure is to be disregarded, and pain is to be despised. And as all moral action must be in harmony with nature, the law of destiny is supreme, and all things move according to immutable fate. With the predominant tendency to the universal which characterized their system, the Stoics taught that the sage ought to regard himself as a citizen of the world rather than of any particular city or state. They made four things to be indispensable to virtue: a knowledge ofgood and evil, which is the province of the reason;temperance, a knowledge of the due regulation of the sensual passions;fortitude, a conviction that it is good to suffer what is necessary; andjustice, or acquaintance with what ought to be to every individual. They madeperfectionnecessary to virtue, and saw nothing virtuous in the mere advance to it. Hence the severity of their system. The perfect sage, according to them, is raised above all influence of external events; he submits to the law of destiny; he is exempt from desire and fear, joy or sorrow; he is not governed even by what he is exposed to necessarily, like sorrow and pain; he is free from the restraints of passion; he is like a god in his mental placidity. Nor must the sage live only for himself, but for others; he is a member of the whole body of mankind; he ought to marry, and to take part in public affairs, but he will never give way to compassion or forgiveness, and is to attack error and vice with uncompromising sternness. But with this ideal, the Stoics were forced to admit that virtue, like true knowledge, although attainable, is beyond the reach of man. They were discontented with themselves, and with all around them, and looked upon all institutions as corrupt. They had a profound contempt of their age, and of human attainments; but it cannot be denied they practiced a lofty and stern virtue, and were the best people in their degenerate times. Their God was made subject to Fate, and he was a material god, synonymous with Nature. Thus their system was pantheistic. But they maintained the dignity of reason, and the ideal in nature, the actualization of which we should strive after, though without the hope of reaching it. "As a reaction against effeminacy, Stoicism may be applauded; as a doctrine, it is one-sided, and ends in apathy and egotism." [Footnote: See Cicero,De Fin. andTusculan Questions; Diogenes Laertius on Zeno. This historian is quite full on this subject, and seems to furnish the basis for Ritter.]
With the Stoics ended all inquiry among the Greeks of a philosophical nature worthy of especial mention, until philosophy was revived in the Christian schools of Alexandria, where faith was united with reason. The Stoics endeavored to establish the certitude of human knowledge in order that they might establish the truth of moral principles, and the basis of their system was common sense, with which they attacked the godless skepticism of their times, and raised up a barrier, feeble though it was, to prevailing degeneracy. The struggles of so many great thinkers, from Thales to Aristotle, all ended in doubt and in despair. It was discovered that all of them were wrong, but that their error was without a remedy.
[Sidenote: Bright period of Grecian philosophy.]
The bright and glorious period of Grecian philosophy was from Socrates to Aristotle. Philosophical inquiries began about the origin of things, and ended with an elaborate systematization of the forms of thought, which was the most magnificent triumph that the unaided intellect of man ever achieved. Socrates founds a school, but does not elaborate a system. He reveals most precious truths, and stimulates the youth who listen to his instructions by the doctrine that it is the duty of man to pursue a knowledge of himself, which is to be sought in that divine reason which dwells within him and which also rules the world. He confides in science; he loves truth for its own sake; he loves virtue, which consists in the knowledge of the good.
[Sidenote: Summary.]
Plato seizes his weapons and is imbued with his spirit. He is full of hope for science and humanity. With soaring boldness he directs his inquiries to futurity, dissatisfied with the present, and cherishing a fond hope of a better existence. He speculates on God and the soul. He is not much interested in physical phenomena. He does not, like Thales, strive to find out the beginning of all things, but the highest good, by which his immortal soul may be refreshed and prepared for the future life he cannot solve, yet in which he believes. The sensible is an impenetrable empire, but ideas are certitudes, and upon these he dwells with rapt and mystical enthusiasm,—a great poetical rhapsodist like Xenophanes, severe dialectician as he is, believing in truth and beauty and goodness.
Then Aristotle, following out the method ofhisteachers, attempts to exhaust experience, and directs his inquiries into the outward world of sense and observation, but all with the view of discovering from phenomena the unconditional truth, in which he, too, believes. But every thing in this world is fleeting and transitory, and, therefore, it is not easy to arrive at truth. A cold doubt creeps into the experimental mind of Aristotle with all his learning and all his logic.
The Epicureans arise. They place their hopes in sensual enjoyment. They despair of truth. But the world will not be abandoned to despair. The Stoics rebuke the impiety which is blended with sensualism, and place their hopes on virtue. But it is unattainable virtue, while their God is not a moral governor, but subject to necessity.
Thus did those old giants grope about, for they did not know the God who was revealed unto Abraham, and Moses, and David, and Isaiah. They solved nothing, since they did notknow, even if they speculated on, theGreat First Cause. And yet, with all their errors, they were the greatest benefactors of the ancient world. They gave dignity to intellectual inquiries, while they set, by their lives, examples of a pure morality—not the morality of the gospel, but the severest virtue practiced by the old guides of mankind.
[Sidenote: Philosophy among the Romans.]
The Romans added absolutely nothing to the philosophy of the Greeks. Nor were they much interested in any speculative inquiries. It was only the ethical views of the old sages which had attraction or force to them. They were too material to love pure subjective inquiries. They had conquered the land; they disdained the empire of the air.
[Sidenote: Followers of the Greeks.]
There were, doubtless, students of the Greek philosophy among theRomans, perhaps as early as Cato the Censor. But there were only twopersons of note who wrote philosophy, till the time of Cicero,Aurafanius and Rubinus, and these were Epicureans.
[Sidenote: Cicero.]
Cicero was the first to systematize the philosophy which contributed so greatly to his intellectual culture. But even he added nothing. He was only a commentator and expositor. Nor did he seek to found a system or a school, but merely to influence and instruct men of his own rank. He regarded those subjects, which had the greatest attraction for the Grecian schools, to be beyond the power of human cognition, and, therefore, looked upon the practical as the proper domain of human inquiry. Yet he held logic in great esteem, as furnishing rules for methodical investigation. He adopted the doctrine of Socrates as to the pursuit of moral good. He regarded the duties which grow out of the relations of human society preferable to the obligations of pursuing scientific researches. Although a great admirer of Plato and Aristotle, he regarded patriotic calls of duty as paramount to any study of science or philosophy, which he thought was involved in doubt. He had a great contempt for knowledge which could neither lead to the clear apprehension of certitude, nor to practical applications. He thought it impossible to arrive at a knowledge of God, or the nature of the soul, or the origin of the world. And he thus was led to look upon the sensible and the present as of more importance than inconclusive inductions, or deductions from a truth not satisfactorily established.
[Sidenote: His eclecticism.]
Cicero was an Eclectic, seizing on what was true and clear in the ancient systems, and disregarding what was simply a matter of speculation. This is especially seen in his treatise "De Finibus Bonorum et Malorum," in which the opinions of all the Grecian schools concerning the supreme good are expounded and compared. Nor does he hesitate to declare that happiness consists in the cognition of nature and science, which is the true source of pleasure both to gods and men. Yet these are but hopes, in which it does not become us to indulge. It is the actual, the real, the practical, which preeminently claims attention; in other words, the knowledge which will but furnish man with a guide and rule of life. [Footnote:De Fin., v. 6.] Indeed, the sum of Philosophy, to the mind of Cicero, is that she is an instructress and a comforter. He takes an entirely practical view of the end of philosophy, which is to improve the mind, and make a man contented and happy. For philosophy as a science,—a series of inductions and deductions,—he had profound contempt. He also regards the doctrines of philosophy as involved in doubt, and even in the consideration of moral questions he is pursued by the conflict of opinions, although, in this department, he is most at home. The points he is most anxious to establish are the doctrines of God and the soul. These are most fully treated in his essay, "De Natura Deorum," in which he submits the doctrines of the Epicureans and the Stoics to the objections of the Academy. [Footnote:De Nat. D., iii. 10.] He admits that man is unable to form true conceptions of God, but acknowledges the necessity of assuming one supreme God as the creator and ruler of all things, moving all things, remote from all mortal mixture, and endued with eternal motion in himself. He seems to believe in a divine providence ordering good to man; in the soul's immortality, in free-will, in the dignity of human nature, in the dominion of reason, in the restraint of the passions as necessary to virtue, in a life of public utility, in an immutable morality, in the imitation of the divine.
[Sidenote: His ethics.]
The doctrines of Cicero on ethical subjects, are chiefly drawn from the Stoics and Peripatetics. They are opinions drawn sometimes from one system and sometimes from another. Thus he agrees with the disciples of Aristotle, that health, honors, friends, country, are worthy objects of desire. Then again, he coincides with the Stoics that passions and emotions of the soul are vices. But he recedes from their severe tone, which elevated the sage too high above his fellow-men.
[Sidenote: Character of his philosophical writings.]
Thus there is little of original thought in the moral theories of Cicero, and these are the result of observation rather than of any philosophical principle. We might enumerate his various opinions, and show what an enlightened mind he possessed; but this would not be the development of philosophy. His views, interesting as they are, and generally wise and lofty, yet do not indicate any progress of the science; He merely repeats earlier doctrines. These were not without their utility, since they had great influence on the Latin fathers. They were esteemed for their general enlightenment. He softened down the extreme views of the great thinkers before his day, and clearly unfolded what had become obscured. He is a critic of philosophy; an expositor whom we can scarcely spare.
If any body advanced philosophy among the Romans, it was Epictetus, and he even only in the realm of ethics. Qumtius Sextius, in the time of Augustus, had revived the Pythagorean doctrines. Seneca had recommended the severe morality of the Stoics, but they added nothing that was not previously known. The Romans had no talent for philosophy, although they were acquainted with its various systems. Their greatest light was a Phrygian slave.
[Sidenote: Epictetus.]
[Sidenote: His lofty ethical system.]
Epictetus taught in the time of Domitian, and though he did not leave any written treatises, his doctrines were preserved and handed down by his disciple Arrian, who had for him the reverence that Plato had for Socrates. The loftiness of his recorded views makes us feel that he must have been indebted to Christianity; for no one, before him, has revealed precepts so much in accordance with its spirit. He was a Stoic, but he held in the highest estimation Socrates and Plato. It is not for the solution of metaphysical questions that he was remarkable. He was not a dialectician, but a moralist, and, as such, takes the highest ground of all the old inquirers after truth. With him, philosophy, as it was to Cicero and Seneca, is a wisdom of life. He sets no value on logic, nor much on physics; but he reveals sentiments of great simplicity and grandeur. His great idea is the purification of the soul. He believes in the severest self-denial; he would guard against the syren spells of pleasure; he would make men feel that, in order to be good, they must first feel that they are evil; he condemns suicide, although it had been defended by the Stoics; he would complain of no one, not even of injustice; he would not injure his enemies; he would pardon all offenses; he would feel universal compassion, since men sin from ignorance; he would not easily blame, since we have none to condemn but ourselves; he would not strive after honor or office, since we put ourselves in subjection to that we seek or prize; he would constantly bear in mind that all things are transitory, and that they are not our own; he would bear evils with patience, even as he would practice self- denial of pleasure; he would, in short, be calm, free, keep in subjection his passions, avoid self-indulgence, and practice a broad charity and benevolence. He felt he owed all to God; that all was his gift, and that we should thus live in accordance with his will; that we should be grateful not only for our bodies, but for our souls, and reason, by which we attain to greatness. And if God has given us such a priceless gift, we should be contented, and not even seek to alter our external relations, which are doubtless for the best. We should wish, indeed, for only what God wills and sends, and we should avoid pride and haughtiness, as well as discontent, and seek to fulfill our allotted part. [Footnote: A fine translation of Epictetus has been published by Little and Brown.]
[Sidenote: Marcus Aurelius.]
Such were the moral precepts of Epictetus, in which we see the nearest approach to Christianity that had been made in the ancient world. And these sublime truths had a great influence, especially on the mind of the most lofty and pure of all the Roman emperors, Marcus Aurelius, wholivedthe principles he had learned from a slave, and whose "Maxims" are still held in admiration.
[Sidenote: General observations.]
Thus did the speculations about the beginning of things lead to elaborate systems of thought, and end in practical rules of life, until, in spirit, they had, with Epictetus, harmonized with many of the revealed truths which Christ and his Apostles laid down for the regeneration of the world. Who cannot see in the inquiries of the old philosopher, whether into nature, or the operations of mind, or the existence of God, or the immortality of the soul, or the way to happiness and virtue, a magnificent triumph of human genius, such as has been exhibited in no other department of human science? We regret that our limits preclude a more extended view of the various systems which the old sages propounded—systems full of errors, yet also marked by important truths, but whether false or true, showing a marvelous reach of the human understanding. Modern researches have discarded many opinions which were highly valued in their day, yet philosophy, in its methods of reasoning, is scarcely advanced since the time of Aristotle; while the subjects which agitated the Grecian schools, have been from time to time revived and rediscussed, and are still unsettled. If any science has gone round in perpetual circles, incapable, apparently, of progression or rest, it is that glorious field of inquiry which has tasked more than any other the mightiest intellects of this world, and which, progressive or not, will never be relinquished without the loss of what is most valuable in human culture.
* * * * *
For original authorities in reference to the matter of this chapter, read Diogenes Laertius' Lives of the Philosophers; the Writings of Plato and Aristotle; Cicero, De Nat., De Or., De Offic., De Div., De Fin., Tusc. Quaest.; Xenophon, Memorabilia; Boethius, De Idea Hist. Phil.; Lucretius.
The great modern authorities are the Germans, and these are very numerous. Among the most famous writers on the history of philosophy, are Bruckner, Hegel, Brandis, I. G. Buhle, Tennemann, Ritter, Plessing, Schwegler, Hermann, Meiners, Stallbaum, and Speugel. The history of Ritter is well translated, and is always learned and suggestive. Tennemann, translated by Morell, is a good manual, brief, but clear. In connection with the writings of the Germans, the great work of Cousin should be consulted.
The English historians of ancient philosophy are not so numerous as the Germans. The work of Enfield is based on Bruckner, or is rather an abridgment. Archer Butler's Lectures are suggestive and able, but discursive and vague, as is the History of Ancient Philosophy by Maurice. Grote has written learnedly on Socrates and the other great lights. Lewes' Biographical History of Philosophy has the merit of clearness, and is very interesting, but rather superficial. Henry has written a good epitome. See also Stanley's History of Philosophy, and the articles in Smith's Dictionary, on the leading ancient philosophers. Donaldson's continuation of Muller's History of the Lit. of Greece, is learned, and should be consulted with Thompson's Notes on Archer Butler. There are also fine articles in the Encyclopedias Britannica and Metropolitana. Schleirmacher, on Socrates, translated by Bishop Thirlwall.
[Sidenote: Wonders of modern science.]
[Sidenote: Every great age distinguished for something never afterwards equaled.]
It would be absurd to claim for the ancients any great attainments in science, such as they made in the field of letters or the realm of art. It is in science, especially when applied to practical life, that the moderns show their great superiority to the most enlightened nations of antiquity. In this great department, modern genius shines with the lustre of the sun. It is this which most strikingly attests the advance of society, which makes their advance a most incontestible fact. It is this which has distinguished and elevated the races of Europe more triumphantly than what has resulted from the combined energies of Greeks and Romans in all other departments combined. With the magnificent discoveries and inventions of the last three hundred years in almost every department of science,—especially in physics, in the explorations of distant seas and continents, in the analysis of chemical compounds, in the explanation of the phenomena of the heavens, in the wonders of steam and electricity, in mechanical appliance to abridge human labor or destroy human life, in astronomical researches, in the miracles which inventive genius has wrought,—seen in our ships, our manufactories, our wondrous instruments, our printing-presses, of our observatories, our fortifications, our laboratories, our mills, our machines to cultivate the earth, to make our clothes, to build our houses, to multiply our means of offense and defense, to make weak children do the work of Titans, to measure our time with the accuracy of the orbit of the planets, to use the sun itself in perpetuating our likenesses to distant generations, to cause a needle to guide the mariner with assurance on the darkest night, to propel a heavy ship against the wind and tide without oars or sails, to make carriages ascend mountains without horses at the rate of thirty miles an hour, to convey intelligence with the speed of lightning from continent to continent, under oceans that ancient navigators never dared to cross; these and other wonders attest an ingenuity and audacity of intellect which would have overwhelmed with amazement the most adventurous of Greeks and the most potent of Romans. The achievements of modern science settle forever the question as to the advance of society and the superiority of modern times over those of the most favored nations of antiquity. But the great discoveries and inventions to which we owe this marked superiority are either accidental or the result of generations of experiment, assisted by an immense array of ascertained facts from which safe inductions can be made. It is not, probably, the superiority of the Teutonic races over the Greeks and Romans to which we may ascribe the wonderful advance of modern society, but the particular direction which genius was made to take. Had the Greeks given the energy of their minds to mechanical forces as they did to artistic creations, they might have made wonderful inventions. But it was so ordered by Providence. Nor was the world in that stage of development when this particular direction of intellect would have been favored. There were some things which the Greeks and Romans exhausted, some fields of labor and thought in which they never have been, and, perhaps, never will be, surpassed; and some future age may direct its energies into channels which are as unknown to us as clocks and steam-engines were to the Greeks. This is the age of mechanism and of science, and mechanism and science sweep every thing before them, and will probably be carried to their utmost capacity and development. Then the human mind may seek some new department, some new scope for energies, and a new age of wonders may arise,—perhaps after the present dominant races shall have become intoxicated with the greatness of their triumphs and have shared the fate of the old monarchies of the East. But I would not speculate on the destinies of the European nations, whether they are to make indefinite advances, until they occupy and rule the whole world, or are destined to be succeeded by nations as yet undeveloped,—savages, as their fathers were when Rome was in the fullness of material wealth and grandeur. We know nothing of the future. We only know that all nations are in the hands of God, who setteth up and pulleth down according to his infinite wisdom.
I have shown that in the field of artistic excellence, in literary composition, in the arts of government and legislation, and even in the realm of philosophical speculations, the ancients were our schoolmasters, and that among them were some men of most marvelous genius, who have had no superiors among us.
[Sidenote: The ancients deficient in the application of science.]
But we do not see the exhibition of genius in what we call science, at least in its application to practical life. It would be difficult to show any department of science which the ancients carried to any degree of perfection. Nevertheless, there were departments in which they made noble attempts, and in which they showed considerable genius, even if they were unsuccessful in great practical results.
[Sidenote: Labors of the ancients in astronomy.]
Astronomy was one of these. So far as mathematical genius is concerned, so far as astronomy taxed the reasoning powers, such men as Eratosthenes, Aristarchus, Hipparchus, and Ptolemy were great lights, of whom humanity may be proud; and, had they been assisted by our modern accidental inventions, they might have earned a fame scarcely eclipsed by that of Kepler and Newton. The Ionic philosophers added but little to the realm of true philosophy, but they were pioneers of thought, and giants in their native powers. The old astronomers did as little as they to place science on a true foundation, but they showed great ingenuity, and discovered some great truths which no succeeding age has repudiated. They determined the circumference of the earth by a method identical with that which would be employed by modern astronomers. They ascertained the position of the stars by right ascension and declination. They knew the obliquity of the ecliptic, and determined the place of the sun's apogee as well as its mean motion. Their calculations on the eccentricity of the moon prove that they had a rectilinear trigonometry and tables of chords. They had an approximate knowledge of parallax. [Footnote: Delambre,Hist. d'Astr. Anc., tom. 1, p. 184.] They could calculate eclipses of the moon, and use them for the correction of their lunar tables. They understood spherical trigonometry, and determined the motions of the sun and moon, involving an accurate definition of the year, and a method of predicting eclipses. They ascertained that the earth was a sphere, and reduced the phenomena of the heavenly bodies to uniform movements of circular orbits. [Footnote: Lewis,Hist. of Astron., p. 209.] We have settled, by physical geography, the exact form of the earth, but the ancients arrived at their knowledge by astronomical reasoning. "The reduction of the motions of the sun, moon, and five planets to circular orbits, as was done by Hipparchus, implies deep concentrated thought and scientific abstraction. The theory of eccentrics and epicycles accomplished the end of explaining all the known phenomena. The resolution of the apparent motions of the heavenly bodies into an assemblage of circular motions, was a great triumph of genius, [Footnote: Whewell,Hist. Induc. Science, v. i. p. 181.] and was equivalent to the most recent and improved processes by which modern astronomers deal with such motions."
But I will not here enumerate the few discoveries which were made by the Alexandrian school. I only wish to show that there are a few names among the ancients which are inscribed on the roll of great astronomers, limited as were the triumphs of the science itself. But, until the time of Aristarchus, most of the speculations were crude and useless. Nothing can be more puerile than the notions of the ancients respecting the nature and motions of the heavenly bodies.
[Sidenote: Astronomy born in Chaldea.]
Astronomy was probably born in Chaldea as early as the time of Abraham. The glories of the firmament were impressed upon the minds of the rude primitive races with an intensity which we do not feel with all the triumphs of modern science. The Chaldean shepherds, as they watched their flocks by night, noted the movements of the planets, and gave names to the more brilliant constellations. Before religious rituals were established, before great superstitions arose, before poetry was sung, before musical instruments were invented, before artists sculptured marble or melted bronze, before coins were stamped, before temples arose, before diseases were healed by the arts of medicine, before commerce was known, before heroes were born, those oriental shepherds counted the hours of anxiety by the position of certain constellations. Astronomy is, therefore, the oldest of the ancient sciences, although it remained imperfect for more than four thousand years. The old Assyrians, Egyptians, and Greeks made but few discoveries which are valued by modern astronomers, but they laid the foundation of the science, and ever regarded it as one of the noblest subjects which could stimulate the faculties of man. It was invested with all that was religious and poetical.
[Sidenote: Discoveries made by oriental nations.]
The spacious level and unclouded horizon of Chaldea afforded peculiar facilities of observation; and its pastoral and contemplative inhabitants, uncontaminated by the vices and superstitions of subsequent ages, active-minded and fresh, discovered, after a long observation of eclipses—some say extending over nineteen centuries—the cycle of two hundred and twenty-three lunations, which brings back the eclipses in the same order. Having once established their cycle, they laid the foundation for the most sublime of all the sciences. Callisthenes transmitted from Babylon to Aristotle a collection of observations of all the eclipses that preceded the conquests of Alexander, together with the definite knowledge which the Chaldeans had collected about the motions of the heavenly bodies. It was rude and simple, and amounted to little beyond the fact that there were spherical revolutions about an inclined axis, and that the poles pointed always to particular stars. The Egyptians also recorded their observations, from which it would appear that they observed eclipses at least one thousand six hundred years before the commencement of our era. Nor is this improbable, if the speculations of modern philosophers respecting the age of the world are entitled to respect. The Egyptians discovered, by the rising of Sirius, that the year consists of three hundred and sixty-five and one quarter days, and this was their sacred year, in distinction from the civil, which consisted of three hundred and sixty-five days. They also had observed the courses of the planets, and could explain the phenomena of the stations and retrogradations, and it is even asserted that they regarded Mercury and Venus as satellites of the sun. Some have maintained that the obelisks which they erected served the purpose of gnomons, for determining the obliquity of the ecliptic, the altitude of the pole, and the length of the tropical year. It is thought that even the Pyramids, by the position of their sides toward the cardinal points, attest their acquaintance with a meridional line. The Chinese boast of having noticed and recorded a series of eclipses extending over a period of three thousand eight hundred and fifty-eight years, and it is probable that they anticipated the Greeks two thousand years in the discovery of the Metonic cycle, or the cycle of nineteen years, at the end of which time the new moons fall on the same days of the year. They determined the obliquity of the ecliptic, one thousand one hundred years before our era, to be 23 degrees 54' 3-15". The Indians, at a remote antiquity, represented celestial phenomena with considerable exactness, and constructed tables by which the longitude of the sun and moon are determined. Bailly thinks that astronomy was cultivated in Siam three thousand one hundred and two years before Christ, which hardly yields in accuracy to that which modern science has built on the theory of universal gravitation. The Greeks divided the heavens into constellations fourteen centuries before Christ. Thales, born 640 B.C., taught the rotundity of the earth, and that the moon shines with reflected light. He also predicted eclipses. Anaximander, born 610 B.C., invented the gnomon, and constructed geographical charts.
[Sidenote: The early Greek investigators.]
But the Greeks, after all, were the only people of antiquity who elevated astronomy to the dignity of a science. They however confessed that they derived their earliest knowledge from the Babylonian and Egyptian priests, while the priests of Thebes asserted that they were the originators of exact astronomical observations. [Footnote: Diod., i. 50.] Diodorus asserts that the Chaldeans used the Temple of Belus, in the centre of Babylon, for their survey of the heavens. [Footnote: Diod., ii. 9.] But whether the Babylonians or the Egyptians were the earliest astronomers, it is of little consequence, although the pedants make it a grave matter of investigation. All we know is, that astronomy was cultivated by both Babylonians and Egyptians, and that they made but very limited attainments. The early Greek philosophers, who visited Egypt and the East in search of knowledge, found very little to reward their curiosity or industry; not much beyond preposterous claims to a high antiquity, and an esoteric wisdom which has not yet been revealed. They approximated to the truth in reference to the solar year, by observing the equinoxes and solstices, and the heliacal rising of particular stars. Plato and Eudoxus spent thirteen years in Heliopolis for the purpose of extracting the scientific knowledge of the priests, but they learned but little beyond the fact that the solar year was a trifle beyond three hundred and sixty-five days. No great names have come down to us from the priests of Babylon or Egypt. No one gained an individual reputation. The Chaldean and Egyptian priests may have furnished the raw material of observation to the Greeks, but the latter alone possessed the scientific genius by which indigested facts were converted into a symmetrical system. The East never gave valuable knowledge to the West. It gave only superstition. Instead of astronomy, it gave astrology; instead of science, it gave magic and incantations and dreams—poison which perverted the intellect. [Footnote: Sir G. G. Lewis,Hist. of Anc. Astron., p. 293.] They connected their astronomy with divination from the stars, and made their antiquity reach back to two hundred and seventy thousand years. There were soothsayers in the time of Daniel, and magicians, exorcists, and interpreters of signs. [Footnote: Dan. i. 4, 17, 20.] They were not men of scientific research, seeking truth. It was power they sought, by perverting the intellect of the people. The astrology of the East was founded on the principle that a star or constellation presided over the birth of an individual, and either portended his fate, or shed a good or bad influence upon his future life. The star which looked upon a child at the hour of his birth, was called the horoscopus, and the peculiar influence of each planet was determined by professors of the genethliac art. The superstitions of Egypt and Chaldea unfortunately spread both among the Greeks and Romans, and these were about all that the western nations learned from the boastful priests of occult science. Whatever was known of real value among the ancients, is due to the earnest inquiries of the Greeks.
[Sidenote: Researches of the Greeks.]
And yet their researches were very unsatisfactory until the time of Hipparchus. The primitive knowledge, until Thales, was almost nothing. The Homeric poems regarded the earth as a circular plain, bounded by the heaven, which was a solid vault or hemisphere, with its concavity turned downwards. And this absurdity was believed until the time of Herodotus, five centuries after; nor was it exploded fully in the time of Aristotle. The sun, moon, and stars, were supposed to move upon, or with, the inner surface of the heavenly hemisphere, and the ocean was thought to gird the earth around as a great belt, into which the heavenly bodies sunk at their setting. [Footnote:Il., vii. 422;Od., iii. i. xix. 433.] Homer believed that the sun arose out of the ocean, ascending the heaven, and again plunging into the ocean, passing under the earth, and producing darkness. [Footnote:Il. viii. 485.] The Greeks even personified the sun as a divine charioteer driving his fiery steeds over the steep of heaven, until he bathed them at evening in the western waves. Apollo became the god of the sun, as Diana was the goddess of the moon. But the early Greek inquirers did not attempt to explain how the sun found his way from the west back again to the east. They merely took note of the diurnal course, the alternation of day and night, the number of the seasons, and their regular successions. They found the points of the compass by determining the recurrence of the equinoxes and solstices; but they had no conception of the ecliptic—of that great circle in the heaven, formed by the sun's annual course, and of its obliquity when compared with the equator. Like the Egyptians and Babylonians, they ascertained the length of the year to be three hundred and sixty-five days; but perfect accuracy was wanting for want of scientific instruments, and of recorded observations of the heavenly bodies. The Greeks had not even a common chronological era for the designation of years. Thus Herodotus informs us that the Trojan War preceded his time by eight hundred years: [Footnote:Il, ii. 53.] he merely states the interval between the event in question and his own time; he had certain data for distant periods. Thus the Greeks reckoned dates from the Trojan War, and the Romans from the building of their city. And they divided the year into twelve months, and introduced the intercalary circle of eight years, although the Romans disused it afterwards until the calendar was reformed by Julius Caesar. Thus there was no scientific astronomical knowledge worth mentioning among the primitive Greeks.
Immense research and learning have been expended by modern critics, to show the state of scientific astronomy among the Greeks. I am equally amazed at the amount of research, and its comparative worthlessness, for what addition to science can be made by an enumeration of the puerilities and errors of the Greeks, and how wasted and pedantic the learning which ransacks all antiquity to prove that the Greeks adopted this or that absurdity. [Transcriber's Note: Lengthy footnote relocated to chapter end.]
[Sidenote: Thales.]
[Sidenote: Anaximander and Anaximenes.]
But to return. The earliest historic name associated with astronomy in Greece was Thales, the founder of the Ionic school of philosophers, born 639 B.C. He is reported to have predicted an eclipse of the sun, to have made a visit to Egypt, to have fixed the year at three hundred and sixty-five days, and to have determined the course of the sun from solstice to solstice. He attributed an eclipse of the moon to the interposition of the earth between the sun and moon; and an eclipse of the sun to the interposition of the moon between the sun and earth. [Footnote: Sir G. G. Lewis,Hist. of Astron., p. 81.] He also determined the ratio of the sun's diameter to its apparent orbit. As he first solved the problem of inscribing a right-angled triangle in a circle, [Footnote: Diog. Laert, i. 24.] he is the founder of geometrical science in Greece. He left, however, nothing to writing, hence all accounts of him are confused. It is to be doubted whether in fact he made the discoveries attributed to him. His speculations, which science rejects, such as that water is the principle of all things, are irrelevant to a description of the progress of astronomy. That he was a great light, no one questions, considering the ignorance with which he was surrounded. Anaximander, who followed him in philosophy, held to puerile doctrines concerning the motions and nature of the stars, which it is useless to repeat. His addition to science, if he made any, was in treating the magnitudes and distances of the planets. He attempted to delineate the celestial sphere, and to measure time by a sun-dial. Anaximenes of Miletus taught, like his predecessors, crude notions of the sun and stars, and speculated on the nature of the moon, but did nothing to advance his science on true grounds, except the construction of sun-dials. The same may be said of Heraclitus, Xenophanes, Parmenides, Anaxagoras. They were great men, but they gave to the world mere speculations, some of which are very puerile. They all held to the idea that the heavenly bodies revolved around the earth, and that the earth was a plain. But they explained eclipses, and supposed that the moon derived its light from the sun. Some of them knew the difference between the planets and the fixed stars. Anaxagoras scouted the notion that the sun was a god, and supposed it to be a mass of ignited stone, for which he was called an atheist.
[Sidenote: Socrates.]
[Sidenote: Pythagoras.]
Socrates, who belonged to another school, avoided all barren speculations concerning the universe, and confined himself to human actions and interests. He looked even upon geometry in a very practical way, so far as it could be made serviceable to land measuring. As for the stars and planets, he supposed it was impossible to arrive at a true knowledge of them, and regarded speculations upon them as useless. The Greek astronomers, however barren were their general theories, still laid the foundation of science. Pythagoras, born 580 B.C., taught the obliquity of the ecliptic, probably learned in Egypt, and the identity of the morning and evening stars. It is supposed that he maintained that the sun was the centre of the universe, and that the earth revolved around it. But this he did not demonstrate, and his whole system was unscientific, assuming certain arbitrary principles, from which he reasoned deductively. "He assumed that fire is more worthy than earth; that the more worthy place must be given to the more worthy; that the extremity is more worthy than the intermediate parts; and hence, as the centre is an extremity, the place of fire is at the centre of the universe, and that therefore the earth and other heavenly bodies move round the fiery centre." But this was no heliocentric system, since the sun moved like the earth, in a circle around the central fire. This was merely the work of the imagination, utterly unscientific, though bold and original. Nor did this hypothesis gain credit, since it was the fixed opinion of philosophers, that the earth was the centre of the universe, around which the sun and moon and planets revolved. But the Pythagoreans were the first to teach that the motions of the sun, moon, and planets, are circular and equable. Their idea that they emitted a sound, and were combined into a harmonious symphony, was exceedingly crude, however beautiful. "The music of the spheres" belongs to poetry, as well as the speculations of Plato.
[Sidenote: Eudoxus.]
Eudoxus, who was born 406 B.C., may be considered the founder of scientific astronomical knowledge among the Greeks. He is reputed to have visited Egypt with Plato, and to have resided thirteen years in Heliopolis, in constant study of the stars, communing with the Egyptian priests. His contribution to the science was a descriptive map of the heavens, which was used as a manual of sidereal astronomy to the sixth century of our era. He distributed the stars into constellations, with recognized names, and gave a sort of geographical description of their position and limits, although the constellations had been named before his time. He stated the periodic times of the five planets visible to the naked eye, but only approximated to the true periods.
The error of only one hundred and ninety days in the periodic time of Saturn, shows that there had been, for a long time, close observations. Aristotle, whose comprehensive intellect, like that of Bacon, took in all forms of knowledge, condensed all that was known in his day in a treatise concerning the heavens. [Footnote: Delambre,Hist. de l'Astron. Anc., tom. i. p. 301.] He regarded astronomy as more intimately connected with mathematical science than any other branch of philosophy. But even he did not soar far beyond the philosophers of his day, since he held to the immobility of the earth—the grand error of the ancients. Some few speculators in science, like Heraclitus of Pontus and Hicetas, conceived a motion of the earth itself upon its axis, so as to account for the apparent motion of the sun, but they also thought it was in the centre of the universe.
[Sidenote: Meton.]
The introduction of the gnomon and dial into Greece advanced astronomical knowledge, since they were used to determine the equinoxes and solstices, as well as parts of the day. Meton set up a sun-dial at Athens in the year 433 B.C., but the length of the hour varied with the time of the year, since the Greeks divided the day into twelve equal parts. Dials were common at Rome in the time of Plautus, 224 B.C.; [Footnote: Ap. Gell.,N. A., iii. 3.] but there was a difficulty of using them, since they failed at night and in cloudy weather, and could not be relied on. Hence the introduction of water-clocks instead.
[Sidenote: Aristarchus.]
Aristarchus is said to have combated (280 B.C.) the geocentric theory so generally received by philosophers, and to have promulgated the hypothesis "that the fixed stars and the sun are immovable; that the earth is carried round the sun in the circumference of a circle of which the sun is the centre; and that the sphere of the fixed stars having the same centre as the sun, is of such magnitude that the orbit of the earth is to the distance of the fixed stars, as the centre of the sphere of the fixed stars is to its surface." [Footnote: Lewis, p. 190.] This speculation, resting on the authority of Archimedes, was ridiculed by him; but if it were advanced, it shows a great advance in astronomical science, and considering the age, was one of the boldest speculations of antiquity. Aristarchus also, according to Plutarch, [Footnote: Plut.,Plac. Phil., ii. 24.] explained the apparent annual motion of the sun in the ecliptic, by supposing the orbit of the earth to be inclined to its axis. There is no evidence that this great astronomer supported his heliocentric theory with any geometrical proof, although Plutarch maintains that he demonstrated it. [Footnote:Quaest. Plat., viii. 1.] This theory gave great offense, especially to the Stoics, and Cleanthes, the head of the school at that time, maintained that the author of such an impious doctrine should be punished. Aristarchus has left a treatise "On the Magnitudes and Distances of the Sun and Moon," and his methods to measure the apparent diameters of the sun and moon, are considered sound by modern astronomers, [Footnote: Lewis, p. 193.] but inexact owing to defective instruments. He estimated the diameter of the sun at the seven hundred and twentieth part of the circumference of the circle, which it describes in its diurnal revolution, which is not far from the truth; but in this treatise he does not allude to his heliocentric theory.
[Sidenote: Archimedes.]
[Sidenote: Eratosthenes.]
Archimedes, born 287 B.C., is stated to have measured the distance of the sun, moon, and planets, and he constructed an orrery in which he exhibited their motions. But it was not in the Grecian colony of Syracuse, but of Alexandria, that the greatest light was shed on astronomical science. Here Aristarchus resided, and also Eratosthenes, who lived between the years 276 and 196 B.C. He was a native of Athens, but was invited by Ptolemy Euergetes to Alexandria, and placed at the head of the library. His great achievement was the determination of the circumference of the earth. This was done by measuring on the ground the distance between Syene, a city exactly under the tropic, and Alexandria situated on the same meridian. The distance was found to be five thousand stadia. The meridional distance of the sun from the zenith of Alexandria, he estimated to be 7 degrees 12', or a fiftieth part of the circumference of the meridian. Hence the circumference of the earth was fixed at two hundred and fifty thousand stadia, not far from the truth. The circumference being known, the diameter of the earth was easily determined. The moderns have added nothing to this method. He also calculated the diameter of the sun to be twenty-seven times greater than of the earth, and the distance of the sun from the earth to be eight hundred and four million stadia, and that of the moon seven hundred and eighty thousand stadia—a very close approximation to the truth.
[Sidenote: Hipparchus.]
[Sidenote: Greatness of Hipparchus.]
Astronomical science received a great impulse from the school of Alexandria, and Eratosthenes had worthy successors in Aristarchus, Aristyllus, Apollonius. But the great light of this school was Hipparchus, whose lifetime extended from 190 to 120 years B.C. He laid the foundation of astronomy upon a scientific basis. "He determined," says Delambre, "the position of the stars by right ascensions and declinations; he was acquainted with the obliquity of the ecliptic. He determined the inequality of the sun, and the place of its apogee, as well as its mean motion; the mean motion of the moon, of its nodes and apogee; the equation of the moon's centre, and the inclination of its orbit; he likewise detected a second inequality, of which he could not, for want of proper observations, discover the period and the law. His commentary on Aratus shows that he had expounded, and given a geometrical demonstration of, the methods necessary to find out the right and oblique ascensions of the points of the ecliptic and of the stars, the east point and the culminating point of the ecliptic, and the angle of the east, which is now called the nonagesimal degree. He could calculate eclipses of the moon, and use them for the correction of his lunar tables, and he had an approximate knowledge of parallax." [Footnote: Delambre,Hist. de l'Astron. Anc., tom. i. p. 184.] His determination of the motions of the sun and moon, and method of predicting eclipses, evince great mathematical genius. But he combined, with this determination, a theory of epicycles and eccentrics, which modern astronomy discards. It was, however, a great thing to conceive of the earth as a solid sphere, and reduce the phenomena of the heavenly bodies to uniform motions in of circular orbits. "That Hipparchus should have succeeded in the first great steps of the resolution of the heavenly bodies into circular motions is a circumstance," says Whewell, "which gives him one of the most distinguished places in the roll of great astronomers." [Footnote:Hist. Ind. Science, vol. i. p. 181.] But he even did more than this. He discovered that apparent motion of the fixed stars round the axis of the ecliptic, which is called the Precession of the Equinoxes, one of the greatest discoveries in astronomy. He maintained that the precession was not greater than fifty- nine seconds, and not less than thirty-six seconds. Hipparchus framed a catalogue of the stars, and determined their places with reference to the ecliptic, by their latitudes and longitudes. Altogether, he seems to have been one of the greatest geniuses of antiquity, and his works imply a prodigious amount of calculation.
[Sidenote: Posidonius.]
[Sidenote: The Roman Calendar.]
Astronomy made no progress for three hundred years, although it was expounded by improved methods. Posidonius constructed an orrery, which exhibited the diurnal motions of the sun, moon, and five planets. Posidonius calculated the circumference of the earth to be two hundred and forty thousand stadia by a different method from Eratosthenes. The barrenness of discovery, from Hipparchus to Ptolemy, in spite of the patronage of the Ptolemies, was owing to the want of instruments for the accurate measure of time, like our clocks, to the imperfection of astronomical tables, and to the want of telescopes. Hence the great Greek astronomers were unable to realize their theories. Their theories were magnificent, and evinced great power of mathematical combination; but what could they do without that wondrous instrument by which the human eye indefinitely multiplies its power?—by which objects are distinctly seen, which, without it, would be invisible? Moreover, the ancients had no accurate almanacs, since the care of the calendar belonged to the priests rather than to the astronomers, who tampered with the computation of time for temporary and personal objects. The calendars of different communities differed. Hence Julius Caesar rendered a great service to science by the reform of the Roman calendar, which was exclusively under the control of the college of pontiffs. The Roman year consisted of three hundred and fifty-five days, and, in the time of Caesar, the calendar was in great confusion, being ninety days in advance, so that January was an autumn month. He inserted the regular intercalary month of twenty-three days, and two additional ones of sixty-seven days. These, together of ninety days, were added to three hundred and sixty-five days, making a year of transition of four hundred and forty-five days, by which January was brought back to the first month in the year after the winter solstice. And to prevent the repetition of the error, he directed that in future the year should consist of three hundred and sixty-five and one quarter days, which he effected by adding one day to the months of April, June, September, and November, and two days to the months of January, Sextilis, and December, making an addition of ten days to the old year of three hundred and fifty-five. And he provided for a uniform intercalation of one day in every fourth year, which accounted for the remaining quarter of a day. [Footnote: Suet.,Caesar, 49; Plut.,Caesar, 59.]
"Ille moras solis, quibus in sua signa rediret,Traditur exactis disposuisse notis.Is decies senos tercentum et quinque diebusJunxit; et pleno tempora quarta die.Hic anni modus est. In lustrum accedere debetQuae consummatur partibus, una dies."
[Footnote: Ovid,Fast., iii.]
[Sidenote: Caesar's labors.]
Caesar was a student of astronomy, and always found time for its contemplation. He is said even to have written a treatise on the motion of the stars. He was assisted in his reform of the calendar by Sosigines, an Alexandrian astronomer. He took it out of the hands of the priests, and made it a matter of pure civil regulation. The year was defined by the sun, and not, as before, by the moon.
Thus the Romans were the first to bring the scientific knowledge of the Greeks into practical use; but while they measured the year with a great approximation to accuracy, they still used sun-dials and water-clocks to measure diurnal time. And even these were not constructed as they should have been. The hours on the sun-dial were all made equal, instead of varying with the length of the day, so that the hour varied with the length of the day. The illuminated interval was divided into twelve equal parts, so that, if the sun rose at five A.M. and set at eight P.M., each hour was equal to eighty minutes. And this rude method of measurement of diurnal time remained in use till the sixth century. But clocks, with wheels and weights, were not invented till the twelfth century.
The earlier Greek astronomers did not attempt to fix the order of the planets; but when geometry was applied to celestial movements, the difference between the three superior planets and the two inferior was perceived, and the sun was placed in the midst between them, so that the seven movable heavenly bodies were made to succeed one another in the following order: 1. Saturn; 2. Jupiter; 3. Mars; 4. The Sun; 5. Venus; 6. Mercury; 7. The Moon. Archimedes adopted this order, which was followed by the leading philosophers. [Footnote: Lewis, p. 247.]
[Sidenote: Ptolemy and his system.]
The last great light among the ancients in astronomical science was Ptolemy, who lived from 100 to 170 A.D. in Alexandria. He was acquainted with the writings of all the previous astronomers, but accepted Hipparchus as his guide. He held that the heaven is spherical and revolves upon its axis; that the earth is a sphere, and is situated within the celestial sphere, and nearly at its centre; that it is a mere point in reference to the distance and magnitude of the fixed stars, and that it has no motion. He adopted the views of the ancient astronomers, who placed Saturn, Jupiter, and Mars next under the sphere of the fixed stars, then the sun above Venus and Mercury, and lastly the moon next to the earth. But he differed from Aristotle, who conceived that the earth revolves in an orbit round the centre of the planetary system, and turns upon its axis—two ideas in common with the doctrines which Copernicus afterward unfolded. But even he did not conceive the heliocentric theory that the sun is the centre of the universe. Archimedes and Hipparchus both rejected this theory.
In regard to the practical value of the speculations of the ancient astronomers, it may be said that, had they possessed clocks and telescopes, their scientific methods would have sufficed for all practical purposes. The greatness of modern discoveries lies in the great stretch of the reasoning powers, and the magnificent field they afford for sublime contemplation. "But," as Sir G. Cornwall Lewis remarks, "modern astronomy is a science of pure curiosity, and is directed exclusively to the extension of knowledge in a field which human interests can never enter. The periodic time of Uranus, the nature of Saturn's ring, and the occupation of Jupiter's satellites, are as far removed from the concerns of mankind as the heliacal rising of Sirius, or the northern position of the Great Bear." This may seem to be a utilitarian view with which those philosophers, who have cultivated science for its own sake, finding in the same a sufficient reward, as in truth and virtue, can have no sympathy.
[Sidenote: Result of ancient investigations.]
The upshot of the scientific attainments of the ancients, in the magnificent realm of the heavenly bodies, would seem to be that they laid the foundation of all the definite knowledge which is useful to mankind; while in the field of abstract calculation they evinced reasoning and mathematical powers which have never been surpassed. Eratosthenes, Archimedes, and Hipparchus were geniuses worthy to be placed by the side of Kepler, Newton, and La Place. And all ages will reverence their efforts and their memory. It is truly surprising that, with their imperfect instruments, and the absence of definite data, they reached a height so sublime and grand. They explained the doctrine of the sphere and the apparent motions of the planets, but they had no instruments capable of measuring angular distances. The ingenious epicycles of Ptolemy prepared the way for the elliptic orbits and laws of Kepler, which, in turn, conducted Newton to the discovery of the laws of gravitation—the grandest scientific discovery in the annals of our race.
[Sidenote: Geometry.]
[Sidenote: Ancient Greek geometers.]
[Sidenote: Euclid.]
[Sidenote: Archimedes.]
Closely connected with astronomical science was geometry, which was first taught in Egypt,—the nurse and cradle of ancient wisdom. It arose from the necessity of adjusting the landmarks, disturbed by the inundations of the Nile. Thales introduced the science to the Greeks. He applied a circle to the measurement of angles. Anaximander invented the sphere, the gnomon, and geographical charts, which required considerable geometrical knowledge. Anaxagoras employed himself in prison in attempting to square the circle. Pythagoras discovered the important theorem that in a right-angled triangle the squares on the sides containing the right angle are together equal to the square on the opposite side of it. He also discovered that of all figures having the same boundary, the circle among plane figures and the sphere among solids, are the most capacious. The theory of the regular solids was taught in his school, and his disciple, Archytas, was the author of a solution of the problem of two mean proportionals. Democritus of Abdera treated of the contact of circles and spheres, and of irrational lines and solids. Hippocrates treated of the duplication of the cube, and wrote elements of geometry, and knew that the area of a circle was equal to a triangle whose base is equal to its circumference, and altitude equal to its radius. The disciples of Plato invented conic sections, and discovered the geometrical loci. They also attempted to resolve the problems of the trisection of an angle and the duplication of a cube. To Leon is ascribed that part of the solution of a problem, called itsdetermination, which treats of the cases in which the problem is possible, and of those in which it cannot be resolved. Euclid has almost given his name to the science of geometry. He was born B.C. 323, and belonged to the Platonic sect, which ever attached great importance to mathematics. His "Elements" are still in use, as nearly perfect as any human production can be. They consist of thirteen books,—the first four on plane geometry; the fifth is on the theory of proportion, and applies to magnitude in general; the seventh, eighth, and ninth are on arithmetic; the tenth on the arithmetical characteristics of the division of a straight line; the eleventh and twelfth on the elements of solid geometry; the thirteenth on the regular solids. These "Elements" soon became the universal study of geometers throughout the civilized world. They were translated into the Arabic, and through the Arabians were made known to mediaeval Europe. There can be no doubt that this work is one of the highest triumphs of human genius, and has been valued more than any single monument of antiquity. It is still a text-book, in various English translations, in all our schools. Euclid also wrote various other works, showing great mathematical talent. But, perhaps, a greater even than Euclid was Archimedes, born 287 B.C., who wrote on the sphere and cylinder, which terminate in the discovery that the solidity and surface of a sphere are respectively two thirds of the solidity and surface of the circumscribing cylinder. He also wrote on conoids and spheroids. "The properties of the spiral, and the quadrature of the parabola were added to ancient geometry by Archimedes, the last being a great step in the progress of the science, since it was the first curvilineal space legitimately squared." Modern mathematicians may not have the patience to go through his investigations, since the conclusions he arrived at may now be reached by shorter methods, but the great conclusions of the old geometers were only reached by prodigious mathematical power. Archimedes is popularly better known as the inventor of engines of war, and various ingenious machines, than as a mathematician, great as were his attainments. His theory of the lever was the foundation of statics, till the discovery of the composition of forces in the time of Newton, and no essential addition was made to the principles of the equilibrium of fluids and floating bodies till the time of Stevin in 1608. He detected the mixture of silver in a crown of gold which his patron, Hiero of Syracuse, ordered to be made, and he invented a water-screw for pumping water out of the hold of a great ship he built. He used also a combination of pulleys, and he constructed an orrery to represent the movement of the heavenly bodies. He had an extraordinary inventive genius for discovering new provinces of inquiry, and new points of view for old and familiar objects. Like Newton, he had a habit of abstraction from outward things, and would forget to take his meals. He was killed by Roman soldiers when Syracuse was taken, and the Sicilians so soon forgot his greatness that in the time of Cicero they did not know where his tomb was. [Footnote: See article in Smith'sDictionary, by Prof. Darkin, of Oxford.]