Miscellanies 2.18.94

But those who kick the bellies of certain animals before they give birth, so as to feast on flesh mixed with milk, have made the womb, created for birth, a tomb for the unborn, though the lawgiver expressly commands: “But you shall not boil a lamb in its mother's milk.” For let not the food of the living animal become a seasoning for the slain one, it says, the flesh; and let not the cause of life become a helper in the consuming of the body. The same law orders that an ox treading out grain not be muzzled; for the worker too must be counted worthy of food. And it forbids yoking an ox and a donkey together to plow the land, perhaps aiming at what is unsuitable between the animals, but at the same time showing that one must not wrong anyone of another nation and bring him under the yoke, when there is nothing to accuse him of except that he is of another race, which is no charge, being neither vice nor arising from vice. But to me the allegory also seems to indicate that one must not share the husbandry of the Word equally with the clean and the unclean, the faithful and the unfaithful; because the one, the ox, is clean, while the donkey has been reckoned among the unclean.