At the end of the 19th century, Edward Clarke, a physician in Boston, perceived an alarming shift in American culture: More and more women were enrolling in universities. He argued that women could not handle the rigors of higher education, especially while on their period. “Girls lose health, strength, blood, and nerve, by a regimen that ignores the periodical tides and [the] reproductive apparatus of their organization,” Clarke wrote in his book in 1873, which received considerable attention.

The concept fit in nicely with the larger discussion about women’s health in the medical field. Women were seen as inherently weak and prone to sickness, and doctors prescribed rest for all manner of physical and psychological ailments. (This was also before exercise became a more popular remedy for certain illnesses.) Learning while menstruating, Clarke thought, risked illness and even infertility.

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This argument didn’t sit well with Jacobi, then a physician in New York. To her, Clarke was utterly wrong. Jacobi was a well-regarded doctor, one of the few women practicing medicine in America in the 1870s. She came from a middle-class New York family, the eldest of 11 children. Her interest in anatomy emerged early, when as a young girl she discovered a dead rat in her family’s barn on Staten Island and, as she recalled, felt overcome with the desire to cut open the cadaver and take a peek inside.

Despite some resistance from her father, who worried higher education would abrade her femininity, Jacobi studied at the New York College of Pharmacy and then the Female Medical College of Pennsylvania, as it was known then, where she received a medical degree in 1864. Jacobi got a second medical degree at the École de Médecine in Paris, where she was the first woman to attend.

By these measures, Jacobi was a living contradiction of Clarke’s conclusions. The year Clarke published his book on girls and education, Jacobi was a lecturer at the Woman’s Medical College of the New York Infirmary and treating patients at the clinic. Those who disapproved of women practicing medicine sounded the warnings Clarke did; they argued that strenuous medical work threatened their feminine qualities and reproductive health.

In a rebuttal published in 1877, Jacobi thoroughly dragged Clarke. His recommendations, she wrote, lacked “experimental proof,” relied on “exaggeration of fact,” and served “many interests besides those of scientific truth.” In her view, Clarke’s assertions weren’t medical at all, but a deliberate attempt to bar women from classrooms and offices and to keep them in the home.

Sure, some women experience pain and discomfort during their period, Jacobi said, but menstruation doesn’t ruin the mind. In fact, women were more healthy when they were engaged in activity in general. Jacobi prescribed one of her patients, Charlotte Perkins Gilman, the author of “The Yellow Wallpaper,” a regimen of mental and physical activity for an ailment that now would likely be diagnosed as depression. Jacobi’s treatment proved more successful than the “rest cure” Gilman had previously received from a male doctor.