26 Then they sailed to the country of the Gadarenes, which is opposite Galilee. 27 And when He stepped out on the land, there met Him a certain man from the city who had demons for a long time. And he wore no clothes, nor did he live in a house but in the tombs. 28 When he saw Jesus, he cried out, fell down before Him, and with a loud voice said, “What have I to do with You, Jesus, Son of the Most High God? I beg You, do not torment me!” 29 For He had commanded the unclean spirit to come out of the man. For it had often seized him, and he was kept under guard, bound with chains and shackles; and he broke the bonds and was driven by the demon into the wilderness. 30 Jesus asked him, saying, “What is your name?” And he said, “Legion,” because many demons had entered him. 31 And they begged Him that He would not command them to go out into the abyss. 32 Now a herd of many swine was feeding there on the mountain. So they begged Him that He would permit them to enter them. And He permitted them. 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 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.
Augustine the Blessed in his Homily 6 on First John said:
“The demons besought the Lord, when He expelled them from the man, that they might be permitted to go into the swine. Should the Lord not have power to tell them not to approach even those creatures? For, had it not been His will to permit this, they were not about to rebel against the King of heaven and earth. But with a view to a certain mystery, with a certain ulterior meaning, He let the demons go into the swine: to show that the devil has dominion in them that lead the life of the swine.”
St. Clementine in his Homily 19 said:
“…how does it not fear Him as superior, as trembling through earthquakes it confesses, and as, though its billows ran high, yet, when the Teacher was sailing on it and commanded a calm, it immediately obeyed and became still? What! Did not the demons go out through fear and respect for Him, and others of them desired to enter into swine; but they first entreated Him before going, plainly because they had no power to enter even into swine without His permission?”
St. Athanasius in his Life of St. Anthony wrote:
“…we ought to fear God only, and despise the demons, and be in no fear of them. But the more they do these things the more let us intensify our discipline against them, for a good life and faith in God is a great weapon. At any rate they fear the fasting, the sleeplessness, the prayers, the meekness, the quietness, the contempt of money and vainglory, the humility, the love of the poor, the alms, the freedom from anger of the ascetics, and, chief of all, their piety towards Christ. Wherefore they do all things that they may not have any that trample on them, knowing the grace given to the faithful against them by the Saviour, when He says, ‘Behold I have given to you power to tread upon serpents and scorpions, and upon all the power of the enemy.” (Lk. 10:19)