Among the animal sacrifices that cause impurity to their participants, the most mysterious and paradoxical is that of the Red Cow, the animal whose ashes, mixed with water, provide the means of purification from the most severe impurity of all, corpse-impurity.

The Red Cow is the sacrifice that breaks all the rules, and reduced the rabbis to such mystification that they declared that even Solomon, in all his wisdom, did not understand it. Their puzzlement derived from the mixture of purity and impurity in the rite of the Red Cow. Its overall purpose was purification; yet in both the preparation and performance of the rite, participants became unclean. There is an ambiguity about the whole procedure that reflects an ambiguity in the concept of impurity itself.

Numbers 19:2 tells us that the Red Cow must be ‘without spot, wherein is no blemish, and upon which never came yoke’. The priest must bring the Red Cow outside the camp, where she is to be killed, ‘before his face’. The priest must take some of the blood of the cow on his finger, and sprinkle it seven times in the direction of the Temple. Then the cow is to be burnt before the priest, ‘in his sight’: ‘her skin, and her flesh, and her blood, with her dung, shall he burn.’ The priest then takes cedar wood, hyssop and scarlet wool, and throws them into the burning cow.

At this point, impurity appears. The officiating priest is now unclean, and must wash his clothes and body in the ritual pool.