First documented in the Divine Farmer’s Materia Medica Classic of the first or second century, the bark of the mimosa tree, known as he huan pi (“collective happiness bark”), is thought to harmonize the emotions and render a person worry-free. The manual advises that “protracted taking may make the body light, brighten the eyes,” and induce one to feel “as if one had acquired whatever one desired.” Modern practitioners sometimes call it “herbal Prozac.”

“In 1931, when Brave New World was being written, I was convinced that there was still plenty of time,” wrote Aldous Huxley in 1958. He’d thought “the completely organized society, the scientific caste system, the abolition of free will by methodical conditioning, the servitude made acceptable by regular doses of chemically induced happiness” were all far off, but now he had come to feel “a good deal less optimistic.” It seemed his prophecies were “coming true much sooner than I thought they would.”

President Herbert Hoover once praised a group of PR professionals. “You have taken over the job of creating desire,” he said, “and have transformed people into constantly moving happiness machines—machines which have become the key to economic progress.” It was 1928; the Great Depression began the following year.

The Talmud tells of a third-century rabbi named Joseph who died, saw a heavenly paradise, returned to life, and told his father of a world to come that would be “the reverse of this one—those who are on top here were below there, and vice versa.” “My son,” said his father, “you have seen a corrected world.”

Misfortune can cause a person unhappiness only when vice has already corrupted them, argued first-century Greek essayist Plutarch. “As a thread saws through the bone that has been soaked in ashes and vinegar, and as men bend and fashion ivory when it has been made soft and pliable by beer,” he wrote in a short piece collected in his Moralia, “so fortune, falling upon that which is of itself ill-affected and soft as the result of vice, gouges it out and injures it.”