There may never have been a topic people thought about more but understood less than their own sexuality. That all changed in 1966 thanks to Virginia Johnson, who died July 24 at 88, and her collaborator, Dr. William Masters, authors of the book Human Sexual Response, a dry but still groundbreaking work that moved beyond the earlier research of Alfred Kinsey, focusing less on sexual behavior and more on basic physiology. Johnson, a onetime country singer and journalist, had no particular sexual expertise–until 1956, when she applied for a job as a research associate at Washington University and was hired by Masters.
Over the years, Masters and Johnson worked with 694 male and female volunteers, wiring them up with every kind of medical sensor available and putting them through their sexual paces while the lab machinery clicked. The book that resulted sold 300,000 copies. The couple, who married in 1971, published numerous other books on sexuality, leaving the world a sexually smarter place.
This text originally appeared in the August 12 issue of TIME magazine.