A man shall not take his father’s wife. Since Moses does not refer here to any other kinds of incest, but speaks only of that with a stepm…

A man shall not take his father's wife
Not marry her, whether his own mother, or a stepmother; or even, as Aben Ezra…

These and similar regulations might have been necessary then, and yet it is not necessary that we scrupulously examine them. The laws relate to the…