After a backlash from Catholics, President Obama on Friday softened his stance on contraceptive coverage in health insurance plans for the employees of religiously affiliated universities and hospitals. Have prohibitions on birth control always been part of Christian dogma?

Not explicitly. The Bible never mentions artificial birth control, although it was certainly practiced in some cultures, even in pre-biblical times. Hippocrates, the father of medicine, described crude contraceptives as early as the fifth century B.C., writing, “If a woman does not wish to become pregnant, give to her in a drink of water moistened copper ore in the amount of a vicia bean, and she will not become pregnant for a year.” That’s actually one of the less repulsive recipes of the time. Another was a supposedly abortion-inducing suppository that included five dismembered Spanish fly beetles, cuttlefish eggs, and sweet wine. A century later, Aristotle prescribed cedar oil and olive oil as spermicides to prevent overpopulation. Modern scientists doubt the efficacy of these methods, but no one has tried testing them. If all else failed—as it surely did quite often—there was infanticide. The Ancient Greeks got around their moral qualms by practicing exposure (i.e., they left newborns to die in the wilderness), allowing a slight chance that the Gods could rescue the infant.

Perhaps the first direct pronouncement against contraception in Christian teachings comes from St. Clement of Alexandria, who in 191 A.D. wrote, “Because of its divine institution for the propagation of man, the seed is not to be vainly ejaculated, nor is it to be damaged, nor is it to be wasted.” Clement based this verdict on several passages from the Bible, including God’s famous command in Genesis, “Be fruitful and multiply.” He also cited the story of Onan, who was punished with death for spilling his seed on the ground.

Modern scholars trace St. Clement’s antipathy to birth control to the Stoics, a school of Greek philosophers whose thinking heavily influenced Christian theology. They counseled that indulgence, including sex for pleasure, led to unhappiness. St. Augustine, in his fifth-century Letters, also drew on Stoic thought when he forcefully denounced all forms of contraception. In his view, sex was a sin even for married couples who were sterile, because they couldn’t produce children.

Such frank discussion of contraception receded from church teachings in medieval times, perhaps because the practice was less common. Birth rates were high, yet population control wasn’t an issue, thanks to high infant mortality rates and short life spans. Besides, general knowledge of the ancients’ birth-control techniques had faded along with other knowledge in the Dark Ages.

The issue resurfaced following the industrial revolution, when the advent of rubber condoms, coupled with urbanization and other social forces, spurred a resurgence of birth control. But as late as the turn of the 20th century, the Catholic Church worried that denouncing contraception would have the unintended consequence of informing people of what it was. Better, the thinking went, to leave them ignorant.

The first official papal pronouncement against contraception didn’t come until 1930. And while Protestant faiths, beginning with Anglicans, took an increasingly lenient stance toward birth control, the Catholic Church reaffirmed its opposition to the practice with Pope Paul VI’s humanae vitae in 1968.

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Explainer thanks David Hunter of the University of Kentucky and Leslie Tentler of the Catholic University of America.

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