Dutch sexologist Jelto Drenth is a vagina man. He celebrates its smells and tastes and feel in The Origin of the World, an eclectic, matter-of-fact survey that includes helpful “how-to” tips as well as a highly satisfactory collection of bizarre facts about women’s private parts. The history of gynecology has its dark episodes: A 19th-century American doctor performs surgical experiments on the vaginal fistulas of black slaves; a Victorian proponent of medical clitoridectomy (often used to treat compulsive masturbation) states, “The patient having been placed completely under the influence of chloroform, the clitoris is freely excised either by scissors or knife—I always prefer the scissors.” But Drenth’s tale is mostly more cheerful than cautionary, with fascinating accounts of the physiology of vaginal response, thoughtful readings of literature, films, and works of art, and a surprising range of trivia. The erudite book displays a brisk and slightly demented sense of humor. When it comes to vibrators, says Drenth, “[r]eal connoisseurs frown upon batteries”; Mattel’s Nimbus 2000 broomstick, part of the Harry Potter marketing craze, vibrated like a sex toy, provoking parental outrage. But the best moments here are moving as well as strange, as when an ultrasound shows a 32-week-old fetus “touch[ing] her own clitoris with her right hand, accompanied by jerky movements of the pelvis and legs.”