Chapter 087 - How The Intellectual Soul Knows Itself and Those Things Which Are in Itself

Since everything is knowable in as far as it is actual, but not as it is potential, our intellect, which is a simple faculty of the intelligible order, knows itself by its action, not by its essence. God, being Pure Actuality, knows by His Essence, not Himself only but all things: angels, whose essence, belonging to the genus of intellectual natures, is neither pure actuality nor complete in itself, know things other than themselves, not by their essence but by similitudes. While the human intellect, which ranks in the genus of intellectual natures as Being in potentia only (like materia prima in the genus of sensible things) is called "possible," because it has the faculty of understanding according as it is actualized through the conversion of material things. Hence the mind knows itself as far as it is actualized through species abstracted from sensible things, made intelligible by the light of the active intellect.

The habit which exists in the mind, and is something midway between pure faculty and pure actuality, is not known except by the act; for nothing is known except as it is actual, which "habit" is not. Hence the knowledge of a habit comes first from the presence of the habit manifested by the act; by which the intellect at once perceives that it has the habit. Secondly, the knowledge of a habit may come through studious investigation, as was said above of the mind.

That, however, which is first understood about the intellect is the fact of its understanding; because intellect is, absolutely speaking, actualized through understanding; while the last understood is its own operation, not tending to others, but remaining in itself.

This, as before said, is perceived by different grades of intellect according to different modes. In God Essence and Understanding are one; in the angels essence is not the same as understanding, nevertheless they know both at once by one simple act; but our intellect is neither our understanding, nor is its essence the immediate object of our understanding, but rather the nature of material things; consequently the latter is the object first known. Thus the act, and by the act the intellect itself, becomes known, the perfection of which consists in this same faculty of understanding. As natural appetite is the inclination consequent upon natural form, so is rational appetite the inclination consequent upon rational form; hence Aristotle says that the will is in the reason. For an inclination exists in anything according to the mode of that thing; hence intelligent inclination, which is the act of the will, is in the intellect intelligibly as in its principle and proper subject. But if it be present intelligibly it follows that it must be understood; therefore the act of the will is understood by the intellect inasmuch as it perceives itself to will: and because it knows the nature of the act, it knows also the nature of the faculty.