PREFACE TO FIRST EDITION
Nearlyall the general truths of Economic Science are, directly or indirectly, truths about the character or the actions of human beings. It is, consequently, always well to warn the readers of economic works, that in Political Economy, more than in any other science, every general rule is fringed with exceptions and modifications; and that instances are never far to seek which seem to prove the reverse of what the general rule states, or to make the statement of it appear inaccurate. But such general rules need be none the less true for this; nor for practical purposes any the less safe to reason from. They resemble, in fact, these general truths with regard tothe seasons, which we do and must reason from, even in so uncertain a climate as our own. It is, for instance, a truth from which we all reason, that summer is dryer and warmer than winter; and yet there is a frequent occurrence of individual days, which, taken by themselves, contradict it. So, too, those economic definitions, the subjects of which are human actions or faculties, can be entirely accurate only in themajorityof cases to which they apply; and these cases will be fringed always by a margin of doubtful ones. But the definitions, for all that, need be none the less practically true. Day and night are fringed with doubtful hours of twilight; but our clear knowledge of how midnight differs from noon is not made less clear by our doubts as to whether a certain hour at sunrise ought to be called an hour of night or morning.
It is especially desirable to prefix thiswarning to a work as short as the present. In larger and more elaborate works, the writer can particularise the more important exceptions and modifications to which his rules and definitions are subject. But in a short work this task must be left to the common sense of the reader. For popular purposes, however, brevity of statement has one great advantage, namely, that of clearness; and, as the significance of the exceptions cannot be understood without the rules, it is almost essential first to state the rules without obscuring them by the exceptions. There are few readers probably who will not see that the general propositions and principles laid down in the following pages, require, in order to fit them to certain cases, various additions and qualifications. It is necessary only for the reader to bear in mind that these propositions need be none the less broadly and vitally true, because any succinct statement of them is unavoidably incomplete.