water becomes impure when it comes into contact with impurity; then, when more water is poured on, it comes into contact with the first, and so on. They say: “Legal analogy would therefore require the impurity to render each successive quantity of water impure, and what is impure cannot remove impurity.”

This is mistaken. They may be asked: “Why do you say that legal analogy requires water to become impure upon contact with impurity?” If they answer, “Because this is so in certain cases,” the response is that those who hold that water becomes impure only when its properties change dispute the ruling in the original case. Those who accept that ruling say: “There is no stronger reason to regard the removal of impurity as contrary to legal analogy than to regard water’s becoming impure as contrary to it. One could instead say that legal analogy requires water not to become impure upon contact with impurity, just as it does not become impure when it comes into contact with it in the course of removing it.”

This analogy is sounder than the former, because scriptural texts and scholarly consensus establish that water removes impurity, whereas whether water becomes impure merely through contact is disputed. How, then, can disputed cases be made evidence against cases on which there is consensus? Proper analogy requires disputed cases to be judged by analogy with cases on which there is consensus.

Furthermore, reason dictates that water does not become impure if the impurity has not altered it. It retains its original created state and is wholesome, falling within the words of the Most High:

“He makes good things lawful for them and forbids them foul things.”

The same legal analogy applies to all liquids when an impurity falls into them and undergoes transformation until its taste is no longer discernible