Q: Whether the Soul Understands All Things Through Innate Species?

A: On the contrary,
The Philosopher, speaking of the intellect, says (De Anima iii, 4) that it is like "a tablet on which nothing is written."

I answer that,
Since form is the principle of action, a thing must be related to the form which is the principle of an action, as it is to that action: for instance, if upward motion is from lightness, then that which only potentially moves upwards must needs be only potentially light, but that which actually moves upwards must needs be actually light. Now we observe that man sometimes is only a potential knower, both as to sense and as to intellect. And he is reduced from such potentiality to act--through the action of sensible objects on his senses, to the act of sensation--by instruction or discovery, to the act of understanding. Wherefore we must say that the cognitive soul is in potentiality both to the images which are the principles of sensing, and to those which are the principles of understanding. For this reason Aristotle (De Anima iii, 4) held that the intellect by which the soul understands has no innate species, but is at first in potentiality to all such species.

But since that which has a form actually, is sometimes unable to act according to that form on account of some hindrance, as a light thing may be hindered from moving upwards; for this reason did Plato hold that naturally man's intellect is filled with all intelligible species, but that, by being united to the body, it is hindered from the realization of its act. But this seems to be unreasonable. First, because, if the soul has a natural knowledge of all things, it seems impossible for the soul so far to forget the existence of such knowledge as not to know itself to be possessed thereof: for no man forgets what he knows naturally; that, for instance, the whole is larger than the part, and such like. And especially unreasonable does this seem if we suppose that it is natural to the soul to be united to the body, as we have established above ([Q. 76] , A. 1): for it is unreasonable that the natural operation of a thing be totally hindered by that which belongs to it naturally. Secondly, the falseness of this opinion is clearly proved from the fact that if a sense be wanting, the knowledge of what is apprehended through that sense is wanting also: for instance, a man who is born blind can have no knowledge of colors. This would not be the case if the soul had innate images of all intelligible things. We must therefore conclude that the soul does not know corporeal things through innate species.

Reply Obj. 1: Man indeed has intelligence in common with the angels, but not in the same degree of perfection: just as the lower grades of bodies, which merely exist, according to Gregory (Homily on Ascension, xxix In Ev.), have not the same degree of perfection as the higher bodies. For the matter of the lower bodies is not totally completed by its form, but is in potentiality to forms which it has not: whereas the matter of heavenly bodies is totally completed by its form, so that it is not in potentiality to any other form, as we have said above (Q. 66, A. 2). In the same way the angelic intellect is perfected by intelligible species, in accordance with its nature; whereas the human intellect is in potentiality to such species.

Reply Obj. 2: Primary matter has substantial being through its form, consequently it had need to be created under some form: else it would not be in act. But when once it exists under one form it is in potentiality to others. On the other hand, the intellect does not receive substantial being through the intelligible species; and therefore there is no comparison.

Reply Obj. 3: If questions be put in an orderly fashion they proceed from universal self-evident principles to what is particular. Now by such a process knowledge is produced in the mind of the learner. Wherefore when he answers the truth to a subsequent question, this is not because he had knowledge previously, but because he thus learns for the first time. For it matters not whether the teacher proceed from universal principles to conclusions by questioning or by asserting; for in either case the mind of the listener is assured of what follows by that which preceded.