Pseudo-Chrysostom — as excerpted in the Catena Aurea on Mark 5:1-20

“(Vict. Ant. e Cat. in Marc.) He wished to shew publicly the fury which devils entertain against men, and that they would inflict much worse things upon men, if they were not hindered by Divine power; because, again, His compassion would not allow this to be shewn on men, He permitted them to enter into the swine, that on them the fury and power of the devils might be made known. There follows: And the unclean spirits went out.”