On The Holy Trinity by St. Augustine
Chapter 8.--Turning Aside from the Image of God.
13. A common nature, therefore, is recognized in their minds, but in their bodies a division of that one mind itself is figured. As we ascend, then, by certain steps of thought within, along the succession of the parts of the mind, there where something first meets us which is not common to ourselves with the beasts reason begins, so that here the inner man can now be recognized. And if this inner man himself, through that reason to which the administering of things temporal has been delegated, slips on too far by over-much progress into outward things, that which is his head moreover consenting, that is, the (so to call it) masculine part which presides in the watch-tower of counsel not restraining or bridling it: then he waxeth old because of all his enemies, viz. the demons with their prince the devil, who are envious of virtue; and that vision of eternal things is withdrawn also from the head himself, eating with his spouse that which was forbidden, so that the light of his eyes is gone from him; and so both being naked from that enlightenment of truth, and with the eyes of their conscience opened to behold how they were left shameful and unseemly, like the leaves of sweet fruits, but without the fruits themselves, they so weave together good words without the fruit of good works, as while living wickedly to cover over their disgrace as it were by speaking well.