Chok (Decree)

After contact with a corpse, a person must be sprinkled with a liquid mixture containing the ashes of a red heifer, together with cedar and ezov, alkaline plants that, when burnt, function as the key ingredients in a detergent.

Although incest taboos are found in the majority of cultures, medieval Jewish thinkers found this to be an insufficient explanation for the Torah’s prohibitions. 

The law of the heifer whose neck is broken, eglah arufah, has puzzled both traditional and modern commentators. What is it meant to accomplish? How does it work?