Photograph by Yale Joel/The LIFE Picture Collection/Getty

To this day, the pill is the only medication we refer to as if it were the only medication. In fact, it’s probably the only object we label quite so generically. As Jonathan Eig points out in his new book, “The Birth of the Pill: How Four Crusaders Reinvented Sex and Launched a Revolution,” there is “no such thing as The Soap or The Vacuum or The Car,” but the oral contraceptive is different. The crusaders of Eig’s book referred to it in that singular way because it was a dream they had chased for so long, a silver bullet that actually turned out to be one. Some of the women who began asking their family doctors for the oral contraceptive when it first went on the market, in 1960, under the brand Enovid, called it “the pill” because it made the request more discreet. But the oral contraceptive—not penicillin or Prozac or Viagra—is still the pill, because it matters so much, in ways both thrillingly intimate and sweepingly sociological.

There were methods of birth control before the pill, of course—condoms, diaphragms, the rhythm method, and, before those, an ingenious trail of desperate measures traceable as far back as ancient Egypt. As Eig nicely puts it, “For as long as men and women have been making babies, they’ve been trying not to.” The ancient Egyptians fashioned vaginal plugs out of crocodile dung. The Greeks imagined that conception could be prevented by anointing the womb with frankincense and myrhh (though I don’t think that’s why the Three Kings were bringing them). The Bible mentioned coitus interruptus. To be reminded of how very, very old these practices are is to be reminded, yet again, of how doomed and absurd and inhumane modern-day political efforts to curb access to contraception really are. After the vulcanization of rubber, in the eighteen-forties, condoms and ill-fitting cervical caps became the most common forms of birth control. And there were others, no more reliable and a good deal more dangerous—Lysol, for instance. In any case, none of these means were readily available to women; as late as 1950, when Eig’s book really gets underway, thirty states and the federal government still had laws on the books preventing the sale of contraception and the dissemination of information about it.

The pill was the first form of birth control that was simultaneously effective (it works to prevent pregnancy roughly ninety per cent of the time, compared to eighty per cent for condoms), easy to use, safe, and under the control of women. It was so much more reliable, in fact, that it allowed women to live quite differently from women of any previous generation, if they chose to. In 2002, the Harvard economists Claudia Goldin and Lawrence Katz published an analysis of the impact of the pill, and found that it “directly lowered the costs of engaging in long-term career investments by giving women far greater certainty regarding the pregnancy consequences of sex.” In other words, after the pill, women could postpone marriage to concentrate on their work without having to give up sex. At first, it was mostly married women who took it, but by the late nineteen-sixties, after a number of states lowered the age of majority, more young single women did. Among the cohort of American women born before 1950, almost fifty per cent had married before the age of twenty-three. Of those born after 1957, fewer than thirty per cent had. In 1970, ten per cent of first-year law students were women; in 1980, the figure was thirty-six per cent. The pill did not create these new ways of living—no medicine or technology alone can do that—but it enabled them.

Eig has written an absorbing history of the pill’s conception and birth. One of the book’s great strengths—accomplished through his smart choice of lead characters—is the depiction of how arduous it is to make real social change. In an era of instant-click donations, ice-bucket challenges, and easy-to-sign online petitions, we sometimes forget that it takes grindingly hard work and the commitment of serious, obsessed, often cranky personalities who are willing to forgo many of the comforts and routines of ordinary life. Margaret Sanger, the first of Eig’s four crusaders, gets the wonderful opening line of the book: “She was an old woman who loved sex and had spent forty years seeking a way to make it better.” But that evokes a crusade a little more fun than it really was. As a young Greenwich Village bohemian in the nineteen-teens and twenties, Sanger “longed,” she recalled, “for romance, dancing, wooing, experience.” And she got them. But she also witnessed the suffering of the women she served as a visiting nurse in the tenements of New York—women wrung out by childbearing, women who died in terrible labors or from botched abortions. Sanger fled to Europe for a year to avoid a jail sentence on obscenity charges; she left her own two small children behind. Her five-year-old daughter died of pneumonia shortly after she returned. She would serve jail time for founding the nation’s first birth-control clinic, in Brooklyn, in 1916. The judge declared, in one of those moments when the niceties of official speech are yanked away to reveal raw animus, that “women did not have the right to copulate with a feeling of security that there will be no resulting conception.” Sanger would make a noxious political alliance with eugenicists, and mute her own belief in sexual freedom, to promote the more anodyne “planned parenthood.”

In 1950, frustrated with the slowing pace of the movement that she’d founded, Sanger tried a bold, new D.I.Y. tactic. She approached a biologist named Gregory Goodwin Pincus, a brilliant “outcast from the scientific establishment” and, in the words of one colleague, “a street-fighting Jew.” Pincus had been fired from Harvard University for his experiments with in-vitro ovulation. When Sanger went to see him, he was conducting his research in a makeshift lab in Worcester, Massachusetts, that he’d raised the money for by going door to door, asking “housewives, plumbers, and hardware store owners to contribute—no donation too small—to a new institution they called the Worcester Foundation for Experimental Biology.” Sanger wanted Pincus to develop a foolproof method of contraception, preferably a pill, and to her surprise he agreed to try.

The research would largely be funded by the book’s Crusader Number Three, Katherine McCormick. (Eig explains that contraception research was of dubious legality at the time, and almost impossible to fund through normal channels.) McCormick’s personal fortune and her commitment to birth control were both born of a family tragedy that had made her single-minded. She was a tall and lovely twenty-nine-year-old suffragist and M.I.T. graduate when, in 1904, she married Stanley McCormick, the heir to the International Harvester fortune. Stanley turned out to be, in the parlance of the day, a raving lunatic. Katherine spent decades pursuing cures for what was ultimately diagnosed as schizophrenia, while trying to keep Stanley from harming himself or others on their secluded estate, Riven Rock. When Stanley died in 1947, leaving her all of his money in a will he’d drafted on their honeymoon, she began funding Pincus to develop a synthetic hormone that would suppress ovulation.

The fourth crusader is a gynecologist named John Rock, who joined Pincus to test the effects of the synthetic hormone progesterone on women. In most ways, Rock had the easiest struggle. A silver-haired man with a formal, gallant manner (and, like Pincus, a wife that he adored), Rock was a Catholic who disagreed with the Church on a few matters: he believed, for example, that a woman’s health took precedence over that of her fetus, and that abortion was acceptable when the mother’s life was in peril; he thought that sex and love went together, and that good sex, free of undue anxiety about pregnancy, kept couples committed. He would recruit and work with the women the pill was tested on—including some in a Massachusetts mental asylum and some in Puerto Rico—leading studies that would certainly not pass human-subject standards today. And, with his soothing bedside manner, he became the public face of a movement to convince ordinary Catholics and the Catholic Church to embrace birth control. He—or, rather, life—convinced most ordinary Catholics. Today, ninety-eight per cent of sexually active Catholic women say that they’ve used contraception, just a shade below non-Catholics. But Rock was never able to persuade the Church. He remained a believing Catholic, but, as he told his daughter, “Religion is a very poor scientist.”