A herd of many swine - The word "herd," here applied to swine, is now commonly given to "cattle." Formerly, it signified any collection of beasts, or even of people.
The number that composed this "herd" was 2,000, Mark 5:13.

A herd of many swine - These were in all probability Jewish property, and kept and used in express violation of the law of God; and therefore their destruction, in the next verse, was no more than a proper manifestation of the justice of God.

And there was (f) a good way off from them an herd of many swine feeding.
(f) On a hill, as Mark and Luke witness: Now Gederah, as Josephus records, book seventeen chapter thirteen, lived after the order of the Greeks and therefore we must not be surprised if there were swine there.

And there was a good way off from them,.... "Nigh unto the mountains", as Mark says, or "on the mountain", as Luke, bordering on the sea shore; so that though it was at some distance, yet within sight. The Vulgate Latin, and the Hebrew edition of Munster read, "not far off"; and the Persic version, "near them": which agree with the accounts of Mark and Luke, who say, that there were "there", or hard by, "an herd of many swine feeding". Since swine's flesh was forbidden the Jews to eat, Leviticus 11:7 it may be asked, how came it to pass, that there should be any number of these creatures, or that such a herd of them should be kept in the land of Israel? To which may be replied, that though the Jews might not eat swine's flesh, they were not forbid to bring them up; which they might do, in order to sell to the Gentiles, who dwelt among them; and particularly to the Romans, under whose government they now were, and with whom swine's flesh was in great esteem: but still a difficulty remains; for it was not only forbidden by the law of God to eat swine's flesh, but, by the Jewish canons, to bring them up, and make any advantage of them in any shape: their law was this, , "an Israelite might not bring up hogs in any place" (r): the reasons of this canon were many, partly because of the uncleanness of these creatures; hence one of their writers (s) observing, that next to those words, they "are unclean unto you", are, "and the swine", says, that this is to teach us, that "it is forbidden to bring up hogs"; and partly, because of the damage which these creatures do to other men's fields: hence (t).
"the wise men say, cursed is he that brings up dogs and hogs, , "because they do much hurt".''
But the chief reason given by the Gemafists (u) for this prohibition, was the fact following:
"When the Hasmonean family, or Maccabees, were at war with one another, Hyrcanus was within (Jerusalem), and Aristobulus without, and every day they let down to them money in a box; and they sent up to them the daily sacrifices: there was one old man who understood the wisdom of the Greeks, and he said unto them, as long as they employ themselves in the service (of God), they will not be delivered into your hands: on the morrow they let down their money, and they sent them up a hog; and when it came to the middle of the wall, he fixed his hoofs in the wall, and the land of Israel shook, &c. at that time they said, cursed be the man , "that breeds hogs"; and cursed is the man that teaches his son the learning of the Grecians.''
Before this time, it seems to have been lawful to bring them up, and trade with them: but now it was forbid, not only to breed them, but to receive any gain or profit by them; for this is another of their rules (w).
"It is forbidden to bring up a hog, in order to get any profit by his skin, or by his lard, or fat, to anoint with, or to light (lamps) with; yea, though it may fall to him by inheritance.''
And nothing was more infamous and reproachful among them, than a keeper of these creatures: when therefore they had a mind to cast contempt upon a man, they would call him (x), "a breeder of hogs", or (y), "a hog herd". But after all, it was only an Israelite that was forbid this; a stranger might bring them up, for this is one of their canons (z).
"A man may sell fetches to give to a stranger that breeds hogs, but to an Israelite it is forbidden to breed them.''
Yea, they say (a),
"If others breed them to anoint skins with their lard, or to sell them to an Israelite to anoint with them, it was lawful: all fat may be sold, which is not for eating.''
And so some cities are supposed to have hogs in them, concerning which they observe (b), that
"a city that has hogs in it, is free from the "mezuzah";''
the schedules which were fastened to the posts of doors and gates: but now supposing this herd of swine belonged to Jews in these parts, it may easily be accounted for; for since they lived among Heathens, they might not have so great a regard to the directions of their Rabbins; and especially, since it was so much for their profit and advantage, they might make no scruple to break through these ordinances. Though this herd of swine may well enough be thought to belong to the Gentiles, that dwelt in this country; since Gadara was a Grecian city, and then inhabited more by Syrians, than by Jews, as Josephus relates (c).
(r) Misn. Bava Kama, c. 7. sect. 7. Midrash Kohelet, fol. 77. 2. (s) Baal Hatturim, in Deut. xiv. 7, 8. (t) Maimon. Nezike Mammon, c. 5. sect. 9. (u) T. Bab. Bava Kama, fol. 82. 2. Menachot, fol. 64. 2. Sota, fol. 49. 2. (w) Tosaphot in Pesach, art. 62. (x) T. Hieros. Shekalim, fol. 47. 3. (y) lb. Trumot, fol. 46. 3. (z) Piske Tosaphot in Sabbat, art. 317. (a) Yom. Tob. & Ez. Chayim, in Misn. Bava Kama, c. 7. sect. 7. (b) Ib. art. 130. (c) De Bello Jude. l. 2. c. 33.

A herd of many swine. According to Mark, 2,000. They were an unclean animal, kept probably by Jews in violation of the spirit of the Mosaic law; or, if by Gentiles, kept in violation of God's law for the land of Israel.

There was a herd of many swine - Which it was not lawful for the Jews to keep. Therefore our Lord both justly and mercifully permitted them to be destroyed.