Luke 8:33

(ubi sup.) But by their being sent down violently into the lake, it is meant that the Church has been purified, and now that the Gentiles are delivered from the dominion of evil spirits, those who refuse to believe in Christ, carry on their unholy rites in hidden places with dark and secret watchings.

But the Lord granted them permission, that this might be among other things to us an occasion of benefit, and the confidence of our safety. It follows, And he suffered them. We must therefore consider that the evil spirits are hostile to those which are subject to them, and this will be evident from their sending down the swine violently into the waters and choking them; as it follows, Then went the devils out of the man and entered into the swine, and the herd ran violently down a steep place into the lake, and were choked. And this Christ permitted to them which sought it, that it might appear from the event how cruel they are. It was also necessary to show that the Son of God has no less power to foresee than the Father, that equal glory might be manifested in each.

Therefore, the demons went out from the man and entered the pigs, and the herd rushed down the steep bank into the lake and was drowned. This signifies that with the Church now glorified, and the people of the Gentiles liberated from the dominion of demons, they who refuse to believe in Christ conduct their sacrilegious rites in hidden places, submerged in blind and profound curiosity. And it should be noted that the unclean spirits would not have gone even into the pigs unless the kind Savior himself had granted their petition, who certainly could have sent them into the abyss. He wanted to teach us a necessary lesson, namely that we should know that they can harm humans even less by their own power, who could not even harm any animals. However, this power, the just and good God can give to us with hidden justice, but not unjustly.