A pagan once approached Rabban Yochanan ben Zakkai — the sage who had smuggled himself out of besieged Jerusalem inside a coffin and refounded Judaism at Yavneh — and said bluntly, "The ceremony of the red heifer looks like witchcraft to me." The laws of Numbers 19 are strange even on their face: a perfect red cow is burned, its ashes mixed with water, and those ashes purify anyone defiled by contact with death.
Yochanan did not argue theology. He asked a practical question: "What do you yourselves do against demoniac possession?" The pagan answered, "We use herbs and fumigations to drive the demon away." Yochanan pressed the logic home. "If herbs and smoke work against evil spirits in your own tradition, why would you not accept that an even more powerful rite works against the demon of impurity — the defilement of death itself?"
The pagan left satisfied. But Yochanan's students stayed behind, uneasy. Had their teacher really believed that the red heifer was only a clever counter-magic? He reassured them gently. "It is a divine statute," he said — a chok, a commandment whose reason lies beyond human inspection. And then he added a deeper teaching: the ashes of the red heifer atone for the sin of the Golden Calf (Exodus 32). A mother cow comes to clean up what her wild child made filthy.
Gaster's Exempla of the Rabbis (1924, No. 33) preserves the two-voiced answer. For the outsider: a familiar argument. For the insider: a divine statute, and a quiet memory of the first Jewish sin.