t is a truth universally acknowledged that Everything Is Funnier With Monkeys. If J. Fred Muggs, Lancelot Link, or zoo-house fecal tossing have taught us anything, it is that every human endeavor is enriched by the addition of a screaming, leg-humping, ass-biting primate. Even, say, sex education. I beg your pardon? you might ask. Clearly you're not acquainted with the strangest children's book of the 19th century—Sammy Tubbs, the Boy Doctor, and Sponsie, the Troublesome Monkey (1874). Written by health crusader and mail-order magnate Dr. Edward Bliss Foote (1829-1906), it's the five-volume Manhattan saga of the 12-year-old son of freed slaves. It does indeed also feature a sidekick monkey named Sponsie—and yes, as promised, he is troublesome.

Sammy is the door-boy for kindly local doctor Samuel Hubbs, a stand-in for Foote himself—they share the same Lexington Avenue address and have written books with the same titles. Sammy Tubbs becomes his young protégé: In a sort of med-school Pygmalion, the older white Hubbs molds the young black Tubbs into a doctor. In each respective volume, amid servant high jinks and literal monkeyshines, Tubbs gets lectured on Muscles, Circulation, Digestion, and the Nervous System. But the fifth and final volume bears a curious inscription on its cover: A Book for Private Reading. Leaf through it, and you'll see why: It has line drawings of genitals, of Rand McNally road-map accuracy.

It's a Victorian sex-ed manual. For children. Starring a monkey.