This power of reflection being denied to animals, it is certain they cannot form ideas, and consequently their consciousness of existence is less sure, and less extensive than ours. Having no idea of time, no knowledge of the past, nor conception of the future, their consciousness of existence is simple, depends solely on the sensations which actually affect them, and consists in the internal sentiment which these sensations produce.
May we not conceive what this consciousness of existence is in animals, by reflecting on our own state when strongly occupied with some object, or violently agitated by some passion, which banishes every reflection upon self? This state we familiarly express by saying, the man is absent or beside himself; and people are in reality beside themselves, when they are occupied with sensations actually present to them, especially if those sensations are so violent and rapid as to allow the mind no time for reflection. When thus situated we feel pleasure and pain in all their varieties; therefore, though seemingly without the participation of the mind, we have a consciousness of our existence. This state, to which we are occasionally exposed, is the habitual state of animals; deprived of ideas, and furnished with sensations, they know not their existence but feel it.
To render more sensible this difference, let us consider minutely the faculties of brutes, and compare them with the actions of man. Like us they have senses, and receive impressions from exterior objects; they have also an interior sense, an organ which retains the agitations occasioned by those impressions, and consequently sensations which, like ours, are renewable, and are more or less strong and durable. But they have neither ingenuity, understanding, nor memory; because they are denied the power of comparing their sensations, and because these three faculties of the mind depend on this power.
Have animals no memory? It will be replied, the contrary seems demonstrably evident. After a considerable absence do they not recognize the persons with whom they had lived, the places where they resided, and the roads which they had frequented? Do they not recollect the punishments, the caresses, the lessons they had received? Though deprived of imagination and understanding, every thing seems still to evince they have a memory active, extensive, and perhaps more faithful than our own. However persuasive these appearances may be deemed, and however strong may be the prejudices created by them, I presume I can demonstrate, that they deceive us, and that brute animals have no knowledge of past events, no idea of time, and of consequence no memory.
In man memory flows from the power of reflection, for the remembrance of things past supposes not only the duration of the impressions on our internal material sense, or renovation of former sensations, but also the comparison which the mind has made of those sensations, or the ideas it has formed. If memory consisted merely in the renovation of past sensations, those sensations would be represented to our internal sense without leaving any determined impressions; they would present themselves without order or connection, as they do in a state of intoxication, or in dreams, when they are so incongruous, and so incoherent, that we immediately lose all recollection of them. Of such things only as have a relation to others, which preceded or followed them, do we retain a remembrance; and every solitary sensation, however powerful, passes away without leaving the smallest trace on the mind. Now it is the mind which establishes these relations of objects, by the comparison it makes between them, and connects our sensations by a continued thread of ideas. As memory consists, then, in a succession of ideas, so it necessarily supposes the power by which ideas are produced.
But, if possible, to leave no doubt on this important point, let us enquire into the nature of that remembrance left by our sensations when they are accompanied with ideas. Pain and pleasure are pure sensations, and the strongest of any, yet we but feebly recollect them, and with confusion. All we remember is, that we were pleased or hurt; but this remembrance is not distinct; we cannot represent to ourselves either the kind, the degree, or the duration of those sensations by which we had been so violently agitated; and the less are we capable of representing those we had but seldom felt. A pain, for example, which we have experienced but once, which only lasted a few minutes, and differed from all former pains, would be soon forgotten; we might recollect we felt great pain, yet, though we distinctly recollected the circumstances which accompanied it, and the period at which it happened, we should have but an imperfect remembrance of the pain itself.
Why is almost every thing forgotten that passed during our infancy? Why have old men a more distinct remembrance of what happened in their prime of life than what occurred in their more advanced years? Can there be a stronger proof that sensations alone are not sufficient to produce memory, and that it exists solely in the train of ideas which our minds derive from those sensations? In infancy the sensations are as lively and rapid as in manhood, yet they leave few or no traces, because at this era the power of reflection, which alone can form ideas is almost totally inactive; and because in the moments it does act, its comparisons are only superficial. In manhood reason is completely developed, because the power of reflection is in full exercise; we then derive from our sensations every possible advantage, and form many orders of ideas, and chains of thought, whereof each, from being often revolved, forms so durable and indelible an impression, that when old age comes on, those very ideas present themselves with more force than those derived from present sensations, because at that period the sensations are feeble, slow and dull, and the mind itself partakes of the languor of the body. In infancy, the time present is every thing; in manhood, we equally enjoy the past, the present and the future; in old age we have little sense of the present, we turn our eyes to the future, and exist in the past. In the infant that prattles, and the old man that dotes, reason is alike imperfect, because they are alike void of ideas; the former is as yet unable to form them, and the latter has ceased.
An idiot, whose corporeal senses and organs appear to be sound, has, like us, sensations of all kinds; he will also have them in the same order, if he lives in society, and is obliged to act as other men. As these sensations do not create in him ideas, as there is no correspondence between his mind and his body, and as he is incapable of reflection, so he is necessarily destitute of memory, and all knowledge of himself. In nothing does such a man differ from a brute, as to the exterior faculties, for though he has a soul, and possesses the principle of reason, yet as this principle remains in a state of inaction, and receives nothing from the corporeal organs, it can have no influence upon his actions which are like those of an animal, solely determined by its sensations, and by a sentiment of its existence and present wants. Thus the idiot and the brute are beings whose operations are in every respect the same, because the one has no soul, and the other makes not any use of it; they are both destitute of the power of reflection, and of course have neither understanding nor memory.
Should it still be said, "Do not the idiot and the brute often act as if they were determined by the knowledge of things past? Do they not distinguish persons with whom they have lived; places where they have resided; and perform many other actions, which necessarily imply memory? And does not all this prove that memory proceeds not from the power of reflection?"