What exactly was the sin of Onan?


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Dear Straight Dope: I read your two-part report on the curse of Noah/Canaan/Ham et al and found it very illuminating. Another enigmatic story in the Bible is the story of Onan. This one has been used to prove that masturbation is evil and punishable by death, so much so that the words masturbation and onanism are synonymous. I’ve read that story over and over, and I’m not sure where people get the masturbation connection. On the surface it seems to me that Onan married his deceased brother’s wife, according to Jewish law, but he did not love her. However, instead of putting her away and leaving her alone, he had sex with her, but didn’t want to have children with her, so he pulled and prayed, thus “spilling his seed on the ground.” My take on it is this: God struck Onan down because he was a rapist who abused his wife, not because he liked to yank his doodle. Or am I just twisting the Bible for my own purposes to alleviate my guilt about spending inordinate amounts of time in the bathroom? Just sign me … Gilbert O’Sullivan, Cleveland, Ohio

SDStaff Dex replies:

You’re right, Onanism and masturbation have been used synonymously in Western cultures, but they probably shouldn’t be. We’ll start with a look at the story as told in Genesis 38:6-10, then show how it was used to justify attitudes towards sex in Judeo-Christian religions.

In the biblical text, Judah, the son of Jacob (called Israel) has three sons, the two of importance to this story being Er and Onan:

Judah got a wife for Er, his first-born; her name was Tamar. But Er, Judah’s first born, was displeasing to the Lord and the Lord took his life. Then Judah said to Onan, Join with your brother’s wife and do your duty by her as a brother-in-law, and provide offspring for your brother. But Onan, knowing that the seed would not count as his, let it go to waste whenever he joined with his brother’s wife, so as not to provide offspring for his brother. What he did was displeasing to the Lord, and He took his life also.

First, the simple explanation of the text.

The death of Er (see note 1 below) without a son makes Onan subject to what is called the levirate law (note 2). Although the law isn’t specifically mentioned until much later in Deuteronomy 25:5, it was very ancient, predating the point at which the Pentateuch was written down (note 3).

Marrying your brother’s wife is forbidden in biblical law, specifically Leviticus 18:16 and 20:21. However, there is an exception if your brother dies without having had a son. In that case, a man is obligated to impregnate his widowed sister-in-law to give his dead brother a son, who becomes the brother’s heir. Deuteronomy 25:5-10 describes a way for the brother to decline this responsibility, but presumably at the time of the story of Onan, that legal mechanism wasn’t known.

Today levirate marriages are rare. Traditional Ashkenazic Jews faced with a brother who’s married, childless, and dead use the Deuteronomic ritual to get out of it. Most Reform and Conservative Jews ignore it altogether. Among Sephardic Jews, one still finds an occasional levirate marriage.

Back to the story. Having no legal means of avoiding his brotherly duty, Onan flatly refuses to do it. He doesn’t object to sex with his brother’s wife; he just doesn’t want to get her with child. We don’t know why except that the child “would not count as his.” Perhaps he lacked a sense of responsibility to the dead. Perhaps he realized that, with Er dead, he would get half his father’s estate, but if Er had an heir, he would only get one-third. So he spilled his seed on the ground. The question is: what exactly does this mean? Religious leaders have advanced different interpretations over the centuries, mostly to justify societal mores.

It’s often difficult to establishing what sex practices various writers meant because they used euphemisms–there wasn’t a technical sexual vocabulary until fairly recently. Also, the authors of commentaries didn’t want to give readers ideas by being too explicit–the “above all, don’t put beans in your ear!” syndrome.

The earliest interpretations were straightforward. What Onan had done was dishonor his dead brother and shirk his obligations. Exactly how he frustrated the purpose of levirate marriage was irrelevant. The text emphasizes the social or legal setting, with Judah describing what Onan has to do and why. The plain reading is that Onan’s sin was refusal to provide his dead brother with an heir.

When religious authorities try to legislate morality, however, the simple meaning of the text is rarely satisfactory. By the rabbinic period (around 100 BC to 300 AD), levirate marriage was no longer widely practiced. Rabbis and early Christian fathers sought other explanations for Onan’s sin, focusing more on the sexual act itself, the spilling of the seed. Jews and Christians adopted sharply different interpretations.

The rabbis interpreted Onan’s transgression as birth control through coitus interruptus. (In a wonderful euphemism, the Jewish commentator Rashi calls this “threshing within, winnowing without.”) They decided what Onan had done was wasteful but not a severe sin; the punishment should be left to God. More generally, the rabbis recognized that intercourse did not always result in pregnancy, and that there could be a purpose to intercourse beyond simple reproduction, namely pleasure.

The Christian church ultimately took a different stance. After four centuries of competition with groups now considered heretical, the Christian church determined that man’s sexual duty was to procreate and replenish the earth, period. Sex for pleasure was weakness, if not outright sinful.

While the Onan story was a factor, the driving force behind Christianity’s evolving attitude toward sex was the New Testament, coupled with the pessimistic certainty that the end of the world was imminent. In the 5th century, St Augustine wrote that while sex is essential to procreation and thus good, sin has corrupted human passion, so copulation for pleasure alone is immoral.

The female role in reproduction was poorly understood–people thought men did the important part, namely planting the seed, and the woman was just the flower pot. Hence, spilling seed (loss of semen) was a grievous sin. This attitude emerged after Cummean, an Irish abbott of the 7th century, set forth penances for various sexual sins. Theodore of Tarsus, also in the 7th century, distinguished onanism from masturbation–he felt onanism was a form of contraception, not just self-pleasuring.

Thomas Aquinas (1225-1274) wrote extensively about sexual subjects; his thinking dominated Christian teaching for centuries. First, he taught that any sexual activity that did not lead to procreation was deviant, even within marriage. Sex without procreation was lust, directed solely at venereal pleasure. Other sexual sins included adultery, rape, and incest.

Second, he set up a category of four “sins against nature” or “unnatural vices.” These are considered more sinful than illicit sex, because they violate the laws of nature as well as the laws of society and the Church. In order from least to worst sinful:

  • Ejaculation without coitus, i.e., masturbation
  • Deviation from the “natural position” (face to face contact, female on her back)
  • Copulation with an “undue sex” (i.e., homosexuality)
  • Copulation with non-human creatures, i.e., bestiality.

The term “sodomy” was used interchangeably with “sins against nature.” All such sins were lumped under the category of “onanism.” Peter Cantor, in the 12th century, had equated sodomy with the sin of Onan because a sodomite “spilled his seed upon the earth.” Sodomy was defined as sexual acts between persons of the same sex, and also “semination in a vessel not ordained for it.”

St. Antonius (1391-1451) used so many euphemisms that we’re not always sure what he was talking about. He used sodomy and onanism interchangeably as “sins against nature” to describe a great variey of sexual activities.

Christian hostility to sex survived all sorts of religious and social upheavals. After the Protestant reformation, both Calvinists and Lutherans condemned onanism. When the Spanish explorers got to the New World, they were appalled to find the Indians engaged not only in cannibalism and human sacrifice but what they considered perverted sex practices such as incest. Spanish missionaries quickly set about forcibly converting the Incas and Aztecs. In North America, the Puritans referred to masturbation as “the solitary vice” and “self-pollution.” Rev. Samuel Danforth (1674) wrote that any ejaculation was “unclean” under divine law.

A few rebelled against Christian beliefs. Jean Jacques Rousseau (1712-1798) wrote that he satisfied his sexual desires by masturbation, but such frank attitudes were rare.

S. A. D. Tissot wrote a monograph on masturbation in 1758 in an early “scientific” effort to interpret sex and religion. Tissot said that seminal emission could cause serious health problems. After all, a boy’s sexual maturation coincided with the deepening of his voice, the growth of body and facial hair, increased height and weight, and other signs of masculinity. Castrated eunuchs produce no semen and are not masculine. Hence, clearly, loss of semen weakened masculinity. Frequent intercourse was dangerous, but loss of semen through “unnatural means” like masturbation was VERY dangerous.

Tissot’s text didn’t reach America until 1832, but his influence was widely felt. According to Tissot, masturbation led to fuzzy thinking and insanity. Madhouse inmates sat around jerking off; ergo, masturbation caused madness. Similar bizarre reasoning led to the belief that masturbation also caused decay of bodily powers, coughing, and consumption (tuberculosis). Female masturbators were prone to hysterical fits, jaundice, or violent cramps.

In the 1800s, onanism and masturbation were tied to homosexuality. Sodomy was a catchall phrase for such practices as masturbation, anal intercourse, and bestiality. Sylvester Graham (1794-1851), inventor of the Graham cracker, taught that the loss of an ounce of semen was equivalent to the loss of four ounces of blood, reducing the life-force and exposing the body to disease and even death. Masturbation was seen as the most dangerous of deviant sexual acts, undoubtedly because it was so extensively practiced. Masturbation was called “the most criminal, most pernicious, most unnatural” of sexual acts, and described as a contagious disease. It was worse than other diseases because it drained off vital bodily fluids. (And you thought Jack D. Ripper’s purity-of-essence bit from Dr. Strangelove was just a nutty Kubrickian riff!)

As the 1800s proceeded, the Victorian Age put hostility to sex on a “scientific” foundation. James Scott, writing in 1899, used the term masturbation to mean any “sin against nature” including coitus interruptus, oral-genital sex, pederasty, bestiality, and self-pollution. Women were warned not to enjoy sex. Contraceptives were condemned as onanism. Infantile paralysis (polio) and infantile rheumatism were added to the list of diseases caused by masturbation.

In the UK, religious and societal attitudes against sex led to a horror of divorce, culminating in the abdication of Edward VIII in1936 to marry a divorced woman.

It’s only in the last century or so that sex–including masturbation–has been viewed as natural, and only in the last few decades that homosexual activities have gained societal acceptance. We’ve come a long way.

One last thing. I’m indebted to George Ertel for pointing out that the term “onanism” is used nowadays in financial circles to indicate premature withdrawal of investments. Truly, these are strange times.


Dear Straight Dope:

I am disappointed to see no acknowledgment of “Gilbert O’Sullivan”‘s little joke in the byline he attached to his onanism/masturbation question: Gilbert O’Sullivan was the man who wrote and sang “Alone Again (Naturally).”

— Soren deSelby

SDStaff Dex and Little Ed reply:

We admit it, that one got past us. We offer only the feeble excuse that the real G. O’S., or anyway the musician who goes by that name, had a hit with that song in 1972, and anyone undistracted enough to remember such things 33 years later … well, no disrespect, but you can see why they’d be interested in onanism.


Note 1: The word “displeasing” is Ra, a pun on Er. The text does not specify the sin.

Note 2. The Hebrew word for this practice is yibbum. In English, “levirate marriage” derives from the Latin levir, a husband’s brother.

Note 3. Sarna (see below) says that laws from the Middle Assyrian Empire (15th-14th century BCE) provided that a widow with no son was to be married off by her father-in-law to the son of his choice. Hittite law (14th-13th century BCE) specified that if a married man died, “his brother shall take his wife.”


David Biale, Eros and the Jew (1992)

Vern L. Bullough, Sexual Variance in Society and History (1976)

Peter Gardella, Innocent Ecstasy (1985)

Nahum M. Sarna, Torah Commentary: Genesis (1989)

SDStaff Dex, Straight Dope Science Advisory Board

Send questions to Cecil via cecil@straightdope.com.