Question: If it is wrong to waste sperm, as the story of Er and Onan demonstrates in the Bible, then can I have sexual relations with my wife after the menopause since biologically she is no longer able to conceive and therefore any sperm is wasted(Question)

Rabbi Naftali Brawer Naftali Brawer is rabbi at Borehamwood and Elstree United Synagogue.

You ask an excellent question. Wasting sperm is a serious prohibition to the extent that the Zohar asserts that it is "more serious than all the sins in the Torah". Yet strangely enough, there is not one reference in the Bible explicitly prohibiting the wasting of sperm. The episode of Er and Onan (Genesis 38: 7-10) presupposes that it is a sin and that is certainly the moral of the story but the Bible does not openly proscribe the act.

This lack of clarity led to a dispute among the rabbis regarding the biblical status of the transgression. There are those who maintain that despite the ambiguity of the biblical text, the prohibition against wasting sperm is nonetheless biblical in origin. Others maintain that it is in essence only a rabbinical proscription. It is not entirely clear why the Bible chooses to avoid any explicit reference to such a severe prohibition. The 18th-century scholar Rabbi Pinchas Elias suggests in his work Sefer Habrit that it is because the sin is so difficult to avoid that the Bible prefers to couch its ban in gentle terms through a narrative rather than unambiguous command. This, says the author, is in keeping with the talmudic principle that it is "better they sin unwittingly rather than knowingly".

While this is certainly a very original approach to a perplexing question, it is not a very strong argument. If it was, the Torah would have avoided explicit references to other severe sins whose temptations prove exceedingly difficult to overcome.

While wasting sperm is sinful, making love to one's spouse is a mitzvah. Lovemaking does not need to be justified by the possibility of conception as these are two distinct mitzvahs. Being fruitful and multiplying is separate from the lesser known mitzvah of onah, which is achieved by giving one's wife sexual pleasure. The Torah asserts that every wife has a right to marital intimacy, regardless of her age and her ability to conceive. If sex was limited only to couples seriously trying for, and capable of conceiving, a child, the majority of couples would never be able to make love and that is certainly not the Torah's intent.

Judaism views the physical union between husband and wife as a holy act. Not as something that is tolerated in order to procreate but rather as an ideal in its own right to be celebrated and cherished.

Rabbi Jonathan Romain Jonathan Romain is rabbi at Maidenhead (Reform) Synagogue.

The question mixes technical details about sexual conduct, key aspects of human relationships and major issues of Jewish authority.

To tackle them in order: in the Onan episode, he practised coitus interruptus and it was deemed sinful. This was then interpreted by rabbinic tradition in a way that went much further than that and forbade any type of sexual intercourse that prevented a man's seed from entering a woman's womb.

This became the basis for a rabbinic ban on condoms (which have that effect), whereas the pill or IUD are permitted. The concern was the method, not contraception itself. Thus there is no problem with sex after menopause, as it does not interfere with the sexual act, while the lack of any child resulting is irrelevant.

It would be wrong to assume that Judaism regards sex as being purely for procreation; it is also for pleasure, both in a physical sense and as way of expressing emotional bonding by coupling together and becoming as one. Abraham and Sarah were clearly having sexual relations well into old age, which is why they were so surprised that she should have conceived long after they thought she was past child-bearing. The Talmud, moreover, goes into graphic detail about husbands acquiring great merit if they restrain themselves during intercourse so that their wives can have an orgasm first and enjoy the experience as much as men do (Niddah 31a-b). Rav Kahana even hid under his teacher's bed to learn how best to give his wife pleasure.

After menopause, therefore, the sperm may not be productive but the sexual act is not interrupted and is certainly permitted, if not encouraged for other purposes. Lifelong sex can be an important part of shalom bayit - domestic harmony - while women are much more than breeding machines.

But should we dictate modern practices according to what happened in Genesis? What was appropriate then does not apply in a world of HIV-AIDS, when not using a condom can be a death-warrant. Condoms should be used rather than shunned. This is not to dismiss the Bible but to acknowledge changing circumstances, where saving life through using a condom is more important than not spilling seed. It would be tragic if the story of an idiotic individual 4,000 years ago blinded us to being sensible about sex today.