These two admonishments regarding various admixtures, whether it be via planting mixed seeds, or wearing clothes of two specific mixed fabrics are analogous with the Torah‘s admonition’s against the intermingling of various opposites. The Chida Zt”l homiletically explains the Torah’s prohibition of planting mixed seeds as being synonymous with one who mixes the performance of a mitzvah with that of a sin. One should not think that by performing the mitzvah of giving charity he now has license to embarrass his friend or slander him, or that spending time praying and studying in the Bais Hamedrash, will counter-balance going to places of entertainment which are morally degrading and destructive. Performing a sin as a follow up to a mitzvah causes the mitzvah to become forfeit. Rabbi Samson Raphael Hirsch Zt”l places emphasis upon the Torah‘s admonishment against wearing shatnez. He states that the Torah is instructing us with reference to our outer clothing which reflects our personalities. We are enjoined to preserve the division between the animal vitality and vegetative instinctiveness that are both part of human nature. We must not subordinate the former to the latter, but rather the latter vegetative urges must be subordinate to the higher animal vivacity, and both then become subordinate to ‘Hashem. This is the fundamental of the calling and mission which ‘Hashem has directed to us. We should not clothe ourselves in a “garment of distortion and perversion” made from mixing two “fabrics” which are to be kept separate, the animal derivative (wool) and the vegetative derivative (linen).
