because whatever falls off the foot will be loose, and it is easy to take the foot out of this leather sock: he can take it out, wash it, dry it, and then put it back in.

Or if part of the foot can be seen through it. If one puts on a leather sock over another leather sock before invalidating his ablution, then the ruling applies to the upper one …

His statement, “Or if part of it can be seen through it,” means that if part of the foot can be seen through the leather sock, one may not wipe over it, even if only a small part is visible. This is based on the previously mentioned condition that the leather sock must cover the part that is obligatory to wash.

This applies whether the foot is visible through a barrier—for example, because the sock is thin or made of plastic—or without any barrier. Thus, if there were a hole in the leather sock the size of a needle’s eye, or if part of it were covered with plastic through which the foot could be seen, then the established position of the school is that wiping over it is not permissible.

It has already been explained that the correct view is that this is permissible (1).

His statement, “If one puts on a leather sock over another leather sock before invalidating his ablution, then the ruling applies to the upper one,” is something that occurs frequently, such as with socks and shoes: this is a leather sock worn over a cloth sock.

According to the established position of the school, it is not permissible to wipe over both of them if they are torn, even if together they cover the foot, because if either one were worn alone, wiping over it would not be permissible. Thus, one may not wipe over them