The first of the firstfruits of thy land thou shalt bring into the house of the LORD thy God. Thou shalt not seethe a kid in his mother's milk. Thou shalt not seethe a kid in his mother's milk - This passage has greatly perplexed commentators; but Dr. Cudworth is supposed to have given it its true meaning by quoting a MS. comment of a Karaite Jew, which he met with, on this passage. "It was a custom of the ancient heathens, when they had gathered in all their fruits, to take a kid and boil it in the milk of its dam; and then, in a magical way, to go about and besprinkle with it all their trees and fields, gardens and orchards; thinking by these means to make them fruitful, that they might bring forth more abundantly in the following year." - Cudworth on the Lord's Supper, 4th.
I give this comment as I find it, and add that Spenser has shown that the Zabii used this kind of magical milk to sprinkle their trees and fields, in order to make them fruitful. Others understand it of eating flesh and milk together; others of a lamb or a kid while it is sucking its mother, and that the paschal lamb is here intended, which it was not lawful to offer while sucking.
After all the learned labor which critics have bestowed on this passage, and by which the obscurity in some cases is become more intense, the simple object of the precept seems to be this: "Thou shalt do nothing that may have any tendency to blunt thy moral feelings, or teach thee hardness of heart." Even human nature shudders at the thought of causing the mother to lend her milk to seethe the flesh of her young one! We need go no farther for the delicate, tender, humane, and impressive meaning of this precept.