Luke 8: 33 Then the demons went out of the man and entered the swine, and the herd ran violently down the steep place into the lake and drowned.34 When those who fed them saw what had happened, they fled and told it in the city and in the country. 35 Then they went out to see what had happened, and came to Jesus, and found the man from whom the demons had departed, sitting at the feet of Jesus, clothed and in his right mind. And they were afraid. 36 They also who had seen it told them by what means he who had been demon-possessed was healed. 37 Then the whole multitude of the surrounding region of the Gadarenes[e] asked Him to depart from them, for they were seized with great fear. And He got into the boat and returned.38 Now the man from whom the demons had departed begged Him that he might be with Him. But Jesus sent him away, saying, 39 “Return to your own house, and tell what great things God has done for you.” And he went his way and proclaimed throughout the whole city what great things Jesus had done for him. (Abbreviated verses)

They are carried violently down, for they are reclaimed not by the contemplation of any good deed, but thrust as from a higher place to a lower, along the downward path of iniquity, they perish amidst the waves of this world, shut out from the approach of air. For they who are carried to and fro by the rapid tide of pleasure cannot receive the communication of the Spirit; we see then that man himself is the author of his own misery. For unless a man lived like the swine, the devil would never have received power over him, or received it, not to destroy but to prove him. And perhaps the devil, who after the coming of our Lord can no longer steal away the good, seeks not the destruction of all men, but only the wanton, as the robber lies in wait not for armed men, but the unarmed.

(St. Ambrose)