SLEEP AND WAKING.
20. The fact of sensation is connected with many others, and from this connection results a great part of our knowledge. It has been said in a tone of great confidence, that it was not possible to demonstrate by sensations the existence of bodies; for as sensations are something purely internal, they cannot enable us to infer the existence of any thing external, and there is no reason for not regarding all our sensations as a collection of individual phenomena, inclosed in our soul. At first view it seems impossible to solve the difficulty; nevertheless, if we examine it thoroughly, we shall see that too great importance has been attached to it.
21. The first objection ordinarily made to the testimony of the senses, is the difficulty of distinguishing with certainty between the state of sleep and that of waking. We receive when asleep impressions similar to those we receive when awake: how shall we know that the illusion is not perpetual? Lamennais, with characteristic exaggeration, says: "He who shall show that all life is not a sleep, an indefinable chimera, will do more than all philosophers have thus far been able to do."
There are here, no doubt, grave difficulties; but we cannot persuade ourselves that they are insolvable. First of all we shall examine if sleep and waking be different, not only in the eyes of common sense, but also in those of reason. Lamennais pretends that only at the tribunal of common consent can a satisfactory and definitive sentence be obtained: we are convinced that very close reasoning can arrive at the same result to which consciousness, common sense, common consent, or, in other words, the testimony of our own being and that of our fellow mortals, conjointly conduce.
22. Man finds in himself a perfectly satisfactory certainty of the difference between sleep and waking: we need no testimony of others to know that we are awake.
The difference between these states must not be solely sought in the clearness and vividness of sensations, and the certainty which they generate. Undoubtedly images are sometimes presented to us in sleep with as much clearness as if we were awake, and our certainty for the instant is complete. Who has not in sleep experienced great joy, or terrible anguish? Sometimes, but very rarely, we have, when we awake, the reminiscence of having in the very act of sleep doubted if we were asleep; but this seldom happens, and it is in general true, that even our dreams are not accompanied by this twilight of reflex reason which warns us of our state and of the illusion that we are under. Ordinarily, while we dream, we have no thought that we are asleep, and we embrace a friend with the same effusion of tenderness, or weep disconsolately over his tomb, with the same affections as we should were all real.
23. The difference is not in momentary uncertainty, for we usually have, on the contrary, complete certainty. Whence, then, is this? How does reason explain it? How does philosophy come to the support of consciousness and common sense? This is the matter we now purpose to examine.
If we abstract sensations having or not having relation to external objects, and also the sufficiency of their testimony in any particular case, and consider them solely as phenomena of our soul, we shall find two orders of facts completely distinguished by marked characters,sleep and waking. In our soul these two orders are totally distinct; even in the system of the idealist this distinction must be recognized.
If we reflect upon what we have experienced since first we had consciousness of what passes within us, we shall observe in our being, two classes of phenomena. Periodically and constantly we experience two series of sensations; some more or less clear, more or less vivid, are confined simply to their object, without the concurrence of many of our faculties, and above all, without reflection upon them; others are always clear, always vivid, accompanied by acts of all our faculties, our reflection upon them, and their difference from those that went before, is entirely subject to our free will in all that is relative; we vary and modify them in a thousand different ways, or suppress and reproduce them.
I see the paper upon which I write; I reflect upon this sight; I abandon and resume it at pleasure; and if I choose, I connect this sensation with others, with a thousand thoughts or different caprices. What takes place in this act, always has happened to me, and always will, whenever that same series of phenomena is produced in me while awake. But if I dream that I write, although it happen not, as it ordinarily does, that I cannot hold my pen exactly right, nor see clearly, but only confusedly, I neither feel the simultaneous exercise of all my faculties, nor reflect upon my present state; I do not have that full consciousness of what I am doing, that clear and strong light which is scattered over all my waking actions and their objects. When awake I think upon what I have done, what I am doing, what I shall do; I recollect my dreams and call them illusions, pronounce them unconnected and extravagant appearances, and compare them with the order and connection of phenomena offered to me whileawake. Nothing of this kind takes place in dreams; I may, perhaps, have a clear, lively sensation but it is independent of my will, it is an isolated impression, the use of only one faculty without the aid of the others, without fixed and constant comparisons, such as I make when awake; and above all, this phenomenon quickly vanishes, and I either fall into a state of unconsciousness of my being, or enter another state in which the same series of phenomena as before is reproduced; they are clear, lucid, connected; they stand the test of reason, which compares them with each other, and with anterior phenomena. Apart, then, from all idea of the external world, and even of all being outside of ourselves, we are certain of the distinction between the two orders of phenomena, those of sleep and those of waking.
Therefore, they who attack the certainty of our cognitions because of the difficulty of distinguishing between these states, make use of a very weak argument, and rely upon a fact entirely false. So far am I from believing it impossible to distinguish philosophically between sleep and waking, that I deem the difference between these two states one of the clearest and most certain facts of our nature.
Having established this truth, and supposing no one to doubt that the sensations experienced in sleep are not produced by external objects, and that, consequently, they cannot be a means of acquiring truth, I pass to another more difficult and important question.