Buffon's Natural History. Volume 05 (of 10) / Containing a Theory of the Earth, a General History of Man, of the Brute Creation, and of Vegetables, Minerals, &c. &c

by comte de Georges Louis Leclerc Buffon

It must already have been perceived, that I distinguish two kinds of memory, infinitely different in their causes, though somewhat similar in their effects. The one consists in the impressions of our ideas; and the other, which I would rather term reminiscence than memory, is nothing more than the renovation of our sensations, or of the vibrations by which they were occasioned. The former issues from the mind, and is much more perfect in man than the latter; which is produced merely by the renovation of the vibrations of the internal sense, and is the only memory possessed by brutes or idiots. Their preceding sensations are renewed by their present ones; the present, and principal, calls forth the former, and the accessory images; they feel as they have felt, and therefore they act as they have acted; they behold together the present and the past, but without distinguishing or comparing, and consequently without knowing them.

As another proof of the existence of memory in animals, I may be told of their dreams. It is certain that brutes, while asleep, have the things represented to them with which they have been occupied while awake. Dogs bark when they are asleep; and though this barking is feeble, yet it is easy to distinguish in it the cry of the chace, accents of rage, sounds of desire, of murmur, &c. It is not to be doubted, then, but that dogs have a lively and active memory, different too from that of which we have now been speaking, since it acts independent of any exterior cause.

To clear up this difficulty, it is necessary to examine the nature of dreams, and to inquire whether they proceed from the mind, or depend entirely on our internal material sense. If we could prove that they reside solely in the latter, it would be an answer to the objection, and another demonstration, that in brutes there is neither understanding nor memory.

Idiots, whose minds are without action, dream like other men; therefore dreams are produced independent of the mind. Let any person reflect upon his dreams, and endeavour to discover why the circumstances are so unconnected, and the events so extravagant. To me it appears, that it is principally because they turn solely upon sensations, and not upon ideas. With the idea of time, for example, they have no affinity. Persons are represented whom we never saw, and even those who have been dead for many years, as alive, and as they formerly were when living; but we indifferently connect them with things and persons of the present, or of a different period. Thus it is also with the idea of place; we must perceive objects where they are not, or we should not see them at all. Did the mind act in a single instant it would give order to this incongruous train of sensations. Instead of which it allows the representations to succeed each other in disorder; and though each object appears in lively colours, the succession is often confused, and always chimerical. If the mind is rather roused by the enormity or force of these sensations, it will in the midst of this darkness produce a spark of light, and create in the midst of chimeras a real idea. We then dream, or rather we will think so, for though this action is but a small sign of the soul, it is yet neither a sensation nor a dream; it is a thought, a reflection, but being too weak to dispel the illusion, it mixes with and forms a part of the dream, and prevents not the representations from succeeding; insomuch, that on awaking, we imagine we had dreamed the very things we had thought.

In dreams we see much, though we but seldom understand; we are powerfully agitated by our sensations, images follow each other, without the least intervention of the mind, either to compare or reconcile them. We have sensations, then, but no ideas, the latter being comparisons of the former; so dreams must reside solely in the internal material sense; and as the mind does not produce them, they must form a part of that animal reminiscence, of which we have already treated. Memory, on the contrary, cannot exist without the idea of time, without a comparison of ideas, and as these extend not to dreams, it seems to be obvious that they can neither be a consequence nor an effect, nor a proof of memory. But though it should be maintained that to some dreams ideas certainly belong; and as a proof of it, those people be quoted who walk, speak, and converse connectedly while asleep; still it would be sufficient for my argument, that dreams may be produced by the renovation of sensations alone, for in consequence thereof the dreams of animals must be merely of this species, and such dreams, far from supposing memory, indicate nothing but a material reminiscence.

By no means am I inclined to believe, that persons who walk and converse while asleep are in reality occupied with ideas. In all such actions the mind seems to have no concern. Sleep-walkers go about, return and act, without reflection or knowledge of their situation or danger; alone are their animal faculties exercised, and even of these some remain unemployed; and while in this state, a sleep-walker is of course more stupid than an idiot. As to persons who speak while asleep, they never say any thing new. An answer to certain common questions, a repetition of a few familiar expressions, may be produced, independent of the principle of thought or action of the mind. Why should we not speak without thought when asleep, since when most awake, and under the influence of passion, man utters numberless things without reflection.

As to the occasional cause of dreams, by which former sensations are renewed without being excited by present objects, it is to be observed, that we never dream when our sleep is sound: every thing is then in a state of inaction, and we sleep both outwardly and inwardly. The internal sense, however, falls asleep the last, and awakes the first, because it is more active, and more easily agitated, than the external senses. It is when our sleep is less sound that we experience illusive dreams, and former sensations, those especially which require not reflection, are renewed. The internal sense being unoccupied by actual sensations from the inaction of the external senses, exercises itself upon its past sensations. Of these the most strong appear the most often; and the more they are strong, the more the situations are extravagant; and for this reason it is, that almost all dreams either terrify or charm us.

That the internal material sense may act of itself, it is not necessary that the exterior senses should be absolutely in a state of repose: it is sufficient if they are without exercise. Accustomed regularly to resign ourselves to repose, we do not easily fall asleep: the body and the members, softly extended, are without motion; the eyes veiled by darkness, the tranquillity of the place, and the silence of the night, render the ear useless; alike inactive are the other senses; all is at rest, though nothing is yet lulled to sleep. In this condition, when the mind is also unoccupied with ideas, the internal material sense is the only power that acts. Then is the time for chimerical images and fluttering shadows. We are awake, and yet we experience the effects of sleep. If we are in full health, the images are agreeable, the illusions are charming; but if the body is disordered or oppressed, then we see grim and hideous phantoms, which succeed each other in a manner not more whimsical than rapid. It is a magic lanthorn, a scene of chimeras, which fill the brain, when destitute of other sensations. We remember our dreams, from the same cause that we remember sensations lately experienced; and the only difference which subsists between us and brutes is, that we can distinguish what belongs to dreams, from what belongs to our real ideas or sensations; and this is a comparison, an operation of the memory, to which the idea of time extends. While brutes, who are deprived of memory, and of this power of comparison, cannot distinguish their dreams, from their real sensations.

I presume, that in treating of the nature of man, I have demonstratively shewn that animals enjoy not the power of reflection. Now the understanding, which is the result of that power, may be distinguished by two different operations. The first is the capacity to compare sensations, and form ideas from them; the second is the faculty to compare ideas themselves, and form arguments or conclusions thereon: by the first we acquire particular ideas, or the knowledge of sensible objects; by the other we form general ideas, which are necessary for the comprehension of abstract truths. Neither of these faculties do the animals possess, because they are void of understanding; and to the first of these operations does the understanding of the bulk of men seem to be limited.