John Lightfoot on Matthew 8:30

[A herd of many swine feeding.] Were these Gadarenes Jews, or heathens?

I. It was a matter of infamy for a Jew to keep swine: "R. Jonah had a very red face, which a certain woman seeing said thus, Seignior, Seignior, either you are a winebibber, or a usurer, or a keeper of hogs."

II. It was forbidden by the canon: "The wise men forbade to keep hogs anywhere, and a dog, unless he were chained." Hogs upon a twofold account: 1. By reason of the hurt and damage that they would bring to other men's fields. Generally, "the keeping smaller cattle was forbid in the land of Israel"; among which you may very well reckon hogs even in the first place: and the reason is given by the Gemarists, "That they break not into other men's grounds." 2. The feeding of hogs is more particularly forbidden for their uncleanness. It is forbidden to trade in any thing that is unclean.

III. Yea, it was forbid under a curse: "The wise men say, Cursed is he that keeps dogs and swine; because from them ariseth much harm."

"Let no man keep hogs anywhere. The Rabbins deliver: When the Asmonean family were in hostility among themselves, Hyrcanus was besieged within Jerusalem, and Aristobulus was without. The besieged sent money in a box let down by a rope; and they which were without bought with it the daily sacrifices, which were drawn up by those that were within. Among the besiegers there was one skilled in the Greek learning, who said, 'As long as they thus perform the service of the Temple, they will not be delivered into your hands.' The next day, therefore, they let down their money, and these sent them back a hog. When the hog was drawing up, and came to the middle of the wall, he fixed his hoofs to the wall, and the land of Israel was shaken, &c. From that time they said, 'Cursed be he who keeps hogs, and cursed be he who teacheth his son the wisdom of the Greeks.'" This story is cited in Menachoth.

Therefore you will wonder, and not without cause, at that which is related in their Talmud: "They said sometimes to Rabh Judah, There is a plague among the swine. He therefore appointed a fast." What! is a Jew concerned for a plague among swine? But the reason is added: "For Rabh Judah thought that a stroke laid upon one kind of cattle would invade all."

You may not, therefore, improperly guess, that these hogs belonged not to the Jews, but to the heathen dwelling among the Gadarene Jews; for such a mixture was very usual in the cities and countries of the land of Israel. Which we observe elsewhere of the town Susitha or Hippo, but some small distance from Gadara.

Or if you grant that they were Jews, their manners will make that opinion probable, as being persons whose highest law the purse and profit was wont to be. Since brawn and swine's flesh were of so great account with the Romans and other heathens, there is no reason to believe that a Jew was held so straitly by his canons, as to value them before his own profit, when there was hope of gain.