Meanwhile, Elijah descended and did not delay. He said: ‘Holy Lamp! Behold this mystery is most certainly the mystery, of: (Deut. 22:10) You shall not plough with an ox and a donkey together. When the first-born – which is Israel, the Middle Pillar – do not bring it the fruit to the house of Y”Y, then milk becomes mixed with meat, and it causes the mingling of ox and donkey, and this is a ‘forbidden-mixture’ (kilayim), of a species with one that is not of its own species.’
Said Rabbi Shim’on: ‘Elijah, Elijah! And yet the ox is from the side of purity, and the donkey is from the side of defilement. This is a ‘forbidden-mixture’ of good and evil! But milk is from the side of purity, and meat is also from the side of purity.’