disliked. If it is uncovered, the reason for its being disliked is clear, because smoke enters it and affects it.

If it is covered and the cover is tightly sealed, it is likewise considered disliked, because it will generally not be free from particles rising into it. The correct view, however, is that if the cover is tightly sealed, it is not disliked.

If smoke enters it and changes it, then this depends on the view as to whether transformation renders an impure substance pure. If we affirm that, then it causes no harm. But if we hold that transformation does not purify, and one of the water’s characteristics is changed by this smoke, then it is impure.

If it changes through remaining for a long time, or through vegetation growing in it, or tree leaves—matters from which it is difficult to protect the water—then …

His statement, “If it changes through remaining for a long time,” means through its prolonged stay. This does not matter, because it has not changed through something newly introduced into it; rather, it changed by itself. Therefore, it is not disliked.

His statement, “or through vegetation growing in it and tree leaves, matters from which it is difficult to protect the water,” refers, for example, to a pond in which grass or algae grows, or into which tree leaves fall, causing it to change. Such water remains purifying and is not disliked, even if its colour, taste, and smell all change. The reason is that avoiding this is difficult. For instance, it would be difficult for someone to keep these trees from the winds so that their leaves do not fall into this place. Likewise, it is difficult for someone to prevent this water from changing as a result of remaining for a long time.

If we were to tell people that such water is pure but not purifying, we would impose hardship upon them.

If it changes because of mud, such as when a man walks in the pond with his feet and takes