John Gill Bible Commentary

And he said unto them, go, &c. He gave them leave, as God did to Satan, in the case of Job; for without divine permission, these evil spirits cannot do anything to the bodies, souls, or estates of men: they could not enter into the swine without leave, and much less do things of greater moment and consequence; and therefore are not to be feared, or dreaded by men, especially by the people of God. It may be asked, why did Christ suffer the devils to enter the herd of swine, and destroy them, which was a considerable loss to the proprietors? To which may be answered, that if the owners were Jews, and these creatures were brought up by them for food, it was a just punishment of their breach of the law of God; or if to be sold to others, for gain and filthy lucre's sake, it was a proper rebuke, both of the avarice and the contempt of the laws of their own country, which were made to be a hedge or fence for the law of God: or if they were Gentiles, this was suffered to show the malice of the evil spirits, under whose influence they were, and who would, if they had but leave, serve them as they did the swine; and to display the power of Christ over the devils, and his sovereign right to, and disposal of the goods and properties of men; and to evince the truth of the dispossession, and the greatness of the mercy the dispossessed shared in; and to spread the fame of the miracle the more. And when they were come out of the men that had been possessed by them, they went into the herd of swine; which shows the real existence of these spirits, the truth of possessions and dispossessions; and that by these devils cannot be meant the sins and corruptions of men's hearts, such as pride, covetousness, uncleanness, envy, malice, cruelty, &c. for these could never be said to enter into a herd of swine, or be the authors of their destruction: and behold, the whole herd of swine, and which was a very large one, consisting of about two thousand, ran violently down a steep place; a precipice of one of the rocks, by the sea side, into the sea of "Tiberias", or lake of Genesareth, which were the same, and over which Christ had just now passed; and perished in the waters of the sea, or lake, and not any other waters near Gadara, and afar off from hence.