Question
Why are mixtures of wool and linen forbidden?
Answer
The laws of Kilayim are “arbitrary” laws (chukim) that have no “logical” rationales. In his Moreh Nevuchim, Maimonides suggests that mixtures of wool and linen may have once been used in garments worn by idol-worshipping priests, so that this specific type of mixture was forbidden as an idolatrous practice. The Torah forbids only mixing linen and sheep’s wool; other mixtures of fibers are permitted, even if one is an animal fiber and the other is a plant fiber.