STOIC DOCTRINES OF SENSATIONS AND MEMORIES HANG TOGETHER.
If we deny that sensations are images impressed on the soul, similar to the impression of a seal,[226] we shall also, for the sake of consistency, have to deny that memories are notions or sensations preserved in the soul by the permanence of the impression, inasmuch as, according to our opinion, the soul did not originally receive any impression. The two questions, therefore, hang together. Either we shall have to insist that sensation consists in an image impressed on the soul, and memory, in its preservation; or, if either one of these opinions be rejected, the other will have to be rejected also. However, since we regard both of them as false, we shall have to consider the true operation of both sensation and memory; for we declare that sensation is as little the impression of an image as memory is its permanence. The true solution of the question, on the contrary, will be disclosed by an examination of the most penetrating sense,[227] and then by induction transferring the same laws to the other senses.
A. OF SENSATION.
THE SENSE OF SIGHT DOES NOT POSSESS THE IMAGE SEEN WITHIN ITSELF.
In general the sensation of sight consists of perception of the visible object, and by sight we attain it in the place where the object is placed before our eyes, as if the perception operated in that very place, and as if the soul saw outside of herself. This occurs, I think, without any image being produced nor producing itself outside of the soul, without the soul receiving any impression similar to that imparted by the seal to the wax. Indeed, if the soul already in herself possessed the image of the visible object, the mere possession of this image (or type) would free her from the necessity of looking outside of herself. The calculation of the distance of the object's location, and visibility proves that the soul does not within herself contain the image of the object. In this case, as the object would not be distant from her, the soul would not see it as located at a distance. Besides, from the image she would receive from within herself, the soul could not judge of the size of the object, or even determine whether it possessed any magnitude at all. For instance, taking as an example the sky, the image which the soul would develop of it would not be so great (as it is, when the soul is surprised at the sky's extent). Besides, there is a further objection, which is the most important of all. If we perceive only the images of the objects we see, instead of seeing the objects themselves, we would see only their appearances or adumbrations. Then the realities would differ from the things that we see. The true observation that we cannot discern an object placed upon the pupil, though we can see it at some little distance, applies with greater cogency to the soul. If the image of the visible object be located within her, she will not see the object that yields her this image. We have to distinguish two things, the object seen, and the seeing subject; consequently, the subject that sees the visible object must be distinct from it, and see it as located elsewhere than within itself. The primary condition of the act of vision therefore is, not that the image of the object be located in the soul, but that it be located outside of the soul.
SENSATIONS ARE NOT EXPERIENCES, BUT RELATIVE ACTUALIZATIONS.
2. After denying that sensation consists of such an operation, it is our duty to point out the true state of affairs. Though it be objected that thus the soul would be considered as judging of things she does not possess, it is nevertheless plain that it is the characteristic of a power, not to experience or suffer, but to develop its force, to carry out the function to which it is destined. If the soul is to discern a visible or audible object the latter must consist of neither images nor experiences, but actualizations relative to the objects which naturally belong to the domain of these actualizations of the soul. Those who deny that any faculty can know its object without receiving some impulsion from it imply that the faculty suffers, without really cognizing the object before it; for this soul-faculty should dominate the object instead of being thereby dominated.
THIS IS TRUE NOT ONLY OF SIGHT BUT OF HEARING, TASTE AND SMELL.
The case of hearing is similar to that of sight. The impression is in the air; the sounds consist in a series of distinct vibrations, similar to letters traced by some person who is speaking. By virtue of her power and her being, the soul reads the characters traced in the air, when they present themselves to the faculty which is suitable to reception of them. As to taste and smell also, we must distinguish between the experience and the cognition of it; this latter cognition constitutes sensation, or a judgment of the experience, and differs therefrom entirely.[228]