Now, should any one say, "And wherefore did Christ fulfill the devils' request, suffering them to depart into the herd of swine?" this would be our reply, that He did so, not as yielding to them, but as providing for many objects thereby.
St. John Chrysostom
Homily 28 on Matthew 8, 4th Century
One, to teach them that are delivered from those wicked tyrants, how great the malice of their insidious enemies: another, that all might learn, how not even against swine are they bold, except He allow them; a third, that they would have treated those men more grievously than the swine, unless even in their calamity they had enjoyed much of God's providential care. For that they hate us more than the brutes is surely evident to every man.
St. John Chrysostom
Homily 28 on Matthew 8, 4th Century