A certain idolater asked Rabban Yoḥanan ben Zakai: ‘These actions that you perform seem to be a type of sorcery. You bring a heifer, burn it, crush it, and take its ashes. One of you becomes impure from a corpse, one sprinkles upon him two or three drops, and you say to him: You are purified.’ He said to him: ‘Has a spirit of insanity never entered you?’
He said to him: ‘No.’ ‘Have you seen a person into whom a spirit of insanity has entered?’ He said to him: ‘Yes.’ He said to him: ‘And what do you do to him?’ He said to him: ‘We bring roots, smoke them beneath him, and sprinkle water on it, and it flees.’
He said to him: ‘Let your ears hear what you express from your mouth. The same is true of this spirit, this spirit of impurity, as it is written: “I will remove the prophets and the spirit of impurity from the land” (Zechariah 13:2). We sprinkle upon it the water of sprinkling, and it flees.’ After he left, his students said to him: ‘You rebuffed this one with a reed.44It was not a particularly compelling response.
What do you say to us?’ He said to them: ‘As you live, it is not the corpse that impurifies, and it is not the water that purifies. Rather, the Holy One blessed be He said: I instituted a statute, issued a decree; you are not permitted to violate My decree, as it is written: “This is the statute of the Torah.”’ Why are all the offerings male and this is female?
Rabbi Aivu said: This is analogous to the son of a maidservant who defecated in a king’s palace. The king said: Let his mother come and wipe the excrement clean. So, the Holy One blessed be He said: Let the heifer come and atone for the act of the calf.