"But when, I take it, the men and the women have passed the age of lawful procreation, we shall leave the men free to form such relations with whomsoever they please, except daughter and mother and their direct descendants and ascendants, and likewise the women, save with son and father, and so on, first admonishing them preferably not even to bring to light anything whatever thus conceived, but if they are unable to prevent a birth to dispose of it on the understanding that we cannot rear such an offspring."