Luke 8 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…

…by the herdsmen of the swine flying and telling these things, He represents certain rulers of the wicked, who though they evade the law of Christianity, yet proclaim it among the nations by their astonishment and wonder. But by the Gerasenes, when they knew what was done, asking Jesus to depart from them, for they were struck with great fear, he represents the multitude delighting in their old pleasures, honouring indeed, but unwilling to endure the Christian law, saying that they cannot fulfil it, while they still marvel at the faithful released from their former abandoned mode of life.

(St Augustine)