X. (35) "He took one of his ribs." He took one of the many powers of the mind, namely, that power which dwells in the outward senses. And when he uses the expression, "He took," we are not to understand it as if he had said, "He took away," but rather as equivalent to "He counted, He examined;" as he says in another place, "Take the chief of the spoils of the captivity." [Nu 31:26.] What, then, is it which he wishes to show? (36) Sensation is spoken of in a twofold manner; --the one kind being according to habit, which exists even when we are asleep, and the other being according to energy. Now, in the former kind, the one according to habit, there is no use: for we do not comprehend any one of the objects presented to our view by its means. But there is use in the second, in that which exists according to energy; for it is by means of this that we arrive at a comprehension of the objects perceptible by the outward senses.
(37) Accordingly, God, having created the former kind of sensation, that existing according to habit, when he was creating the mind (for he was furnishing that with many faculties in a state of rest), desires now to complete the other kind which exists according to energy. And this one according to energy is perfected when the one which exists according to habit is put in motion, and extended as far as the flesh and the organs of sense. For as nature is perfected when the seed is put in motion, so, also, energy is perfected when the habit is put in motion.