“These are the instructions concerning animals, birds, all living creatures that move in water, and all creatures that swarm on earth, for distinguishing between the unclean and the clean, between the living things that may be eaten and the living things that may not be consumed.” (Leviticus 11:46-47)

By legacy, by history – by divine decree, if you like – we are a people of discernment. 

Our tradition gives us such binary categories as pure and...