From his dialogue with a ruler.
Now, O judge, permit me to make use of a comparison. Suppose that you, the ruler of this city, learned that a bear or some other fierce beast was responsible for the destruction of livestock. You gave orders to one of your servants to slay it, but he proved too weak and inexperienced, and was himself killed and eaten. Would you then send another weak, untested servant? No! Being a strong man proven in combat against wild animals, you would yourself dispatch the beast. So doing, you would not hesitate to lay aside your fine apparel and to clothe yourself in the garb of a common huntsman. Better than any words, your example would teach your slaves how to deal with fierce animals. Similarly our Lord, the Saviour of all, seeing His servants defeated in battle against the devil, abased Himself and descended into the womb of the immaculate Virgin. Himself assuming the form of a servant, He was clothed in our flesh while remaining a stranger to sin. He dwelt among mortals, out of humility wisely choosing to conceal His divinity from the wicked devil you worship. In this way He deceived the enemy into taking Him for a simple man. By His saving Passion on the Cross He conquered the adversary, destroying his power and teaching us always to contemplate His contest, do battle with the foe and vanquish him in like manner. Having taken our passions upon Himself, He imparts to us the dispassion that is, and has raised up the dead confined in Hades. His hand is always ready to help us, and He has given us the possibility of becoming children of God. For our struggles we hope to be crowned in heaven, and although death and corruption may conquer our bodies, our spirits remain victorious and immortal.
Therefore, we hate the life you love, an existence no better than an animal's, full of drunkenness and dissipation, and we strive to live like the angels and attain the everlasting abodes prepared for us.