nor anything else can purify it, such as a dog. Even if it were washed seven times, one of them with soil, it would not become pure, because its very substance is impure.

Some scholars held that if an inherently impure substance undergoes transformation, it becomes pure.1 For example, if dung is burned and becomes ashes, the ashes are pure; likewise, if a dog falls into a salt pan and turns into salt, it becomes pure, because it has transformed into something else and its original substance has vanished. Thus, this dog, which had been flesh, bones, and blood, has become salt; the salt has eliminated the original substance.

“And it remains in its original state; but if it changes through something that does not mix with it, such as pieces of camphor …”

His statement, “And it remains in its original state,” is the definition of purifying water, whose explanation has preceded.

His statement, “but if it changes through something that does not mix with it, such as pieces of camphor”: if water changes due to something that does not mix with it, such as pieces of camphor—which is a type of perfume that may come in pieces or as a fine, soft powder rather than pieces—then, when these pieces are placed in the water, they alter its taste and smell, but do not mix with it; that is, they do not dissolve into it. If it changes in this manner, it remains purifying water, though disliked.

If it is asked: How can it remain purifying when it has changed?

The answer is that this change is not caused by mixing, but by proximity. The water has not changed because these pieces have mixed with it, but because they are adjacent to it.

If it is asked: Why is it disliked?