"There is no mention of contraception in the Bible, Old Testament or New, nor did the term enter the vocabulary of Catholic moral theology until the second half of the twentieth century. Before then, the most relevant term used by theologians was onanisma, from the biblical story of Onan (Genesis 38:4–10), which was described as masturbation or sexual intercourse performed without the intention of reproduction. Sex was only for procreation, the Christian church declared, which made onanisma a sin. The human reproductive system was poorly understood even in the early years of the twentieth century. Many people thought women were merely the vessels, and that the man’s seed sprung on its own into a baby. That’s why spilling seed, or losing semen, whether in sex or masturbation, was labeled a sin. Still, the Catholic Church had no official position on birth control until 1930, when Pope Pius XI issued a papal encyclical called “Casti Connubii” (Latin for “Of Chaste Wedlock”). The pope acknowledged that birth control was widely used “even amongst the faithful,” although he wasn’t happy about it, and called this trend “a new and utterly perverse morality.” He added that it amounted to a “shameful and intrinsically vicious” attempt to get around the natural “power and purpose” of the conjugal act. The pope did, however, offer the faithful an important loophole: A married couple would not be sinning, he said, if the husband and wife knew that natural reasons prevented them from having children."