Medieval Advice for the Circumcised

I’ve just come across an extraordinary piece of advice written by a 13th century French rabbi, Isaac ben Yedaiah. I found it on the website, and it attempts to explain, in some detail, why a circumcised man should never allow his wife to sleep with an uncircumcised man:

She will court the man who is uncircumcised in the flesh and lie against his breast with great passion, for he thrusts inside her a long time because of the foreskin, which is a barrier against ejaculation in intercourse. Thus she feels pleasure and reaches an orgasm first. When an uncircumcised man sleeps with her and then resolves to return to his home, she brazenly grasps him, holding on to his genitals, and says to him, “Come back, make love to me.” This is because of the pleasure that she finds in intercourse with him, from the sinews of his testicles – sinews of iron – and from his ejaculation – that of a horse – which he shoots like an arrow into her womb. They are united without separating, and he makes love twice and three times in one night, yet the appetite is not filled.

I’m not really clear why Rabbi ben Yedaiah felt he had to say any of this. Was he answering a congregant’s question? (‘Rabbi, my wife wants to sleep with an uncircumcised man. It couldn’t harm our marriage, could it?’) Or was he recounting how the first Mrs ben Yedaiah had ended up living with her yoga instructor? Either way, he makes the strongest argument against circumcision that I’ve come across for a while.