As, then, Knowledge (ἐπιστήμη) is an intellectual state, from which results the act of knowing, and becomes apprehension irrefragable by reason; so also ignorance is a receding impression, which can be dislodged by reason. And that which is overthrown as well as that which is elaborated by reason, is in our power. Akin to Knowledge is experience, cognition (εἴδησις), Comprehension (σύνεσις), perception, and Science. Cognition (εἴδησις) is the knowledge of universals by species; and Experience is comprehensive knowledge, which investigates the nature of each thing. Perception (νόησις) is the knowledge of intellectual objects; and Comprehension (σύνεσις) is the knowledge of what is compared, or a comparison that cannot be annulled, or the faculty of comparing the objects with which Judgment and Knowledge are occupied, both of one and each and all that goes to make up one reason. And Science (γνῶσις) is the knowledge of the thing in itself, or the knowledge which harmonizes with what takes place. Truth is the knowledge of the true; and the mental habit of truth is the knowledge of the things which are true. Now knowledge is constituted by the reason, and cannot be overthrown by another reason. What we do not, we do not either from not being able, or not being willing—or both. Accordingly we don’t fly, since we neither can nor wish; we do not swim at present, for example, since we can indeed, but do not choose; and we are not as the Lord, since we wish, but cannot be: “for no disciple is above his master, and it is sufficient if we be as the master:” not in essence (for it is impossible for that, which is by adoption, to be equal in substance to that, which is by nature); but [we are as Him] only in our having been made immortal, and our being conversant with the contemplation of realities, and beholding the Father through what belongs to Him.