A 2018 study run at Buttercups Sanctuary in Kent, England, found that goats are sensitive to human emotions and strongly prefer to sniff smiling, happy faces rather than frowning ones.

Not long before his death in 961, Umayyad caliph Abd al-Rahman III testified that over his fifty years of reign, during which “riches and honors, power and pleasure, have waited on my call,” he had “diligently numbered the days of pure and genuine happiness.” Al-Rahman had counted only fourteen. “O man,” he lamented, “place not thy confidence in this present world!”

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.”

A study of U.S. Supreme Court oral transcripts from 2004 to 2005 tabulated every instance the court reporter described a justice’s remarks provoking laughter. It found that Antonin Scalia had caused seventy-seven such episodes, while Clarence Thomas had caused zero.

“Swallowing sunshine is not at all difficult, and it works miracles of power, but some people are too lazy to do it,” wrote Unitarian Universalist clergyman Alden Eugene Bartlett in a 1918 guide to happiness. He advised, however, against swallowing too quickly. “If you have only been existing, half-dead,” he warned, “you will purify your blood so fast it will make you dizzy.”

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.”

“One enterprising seventeenth-century systematizer,” noted classicist Mary Beard in a discussion of the different ways the sounds of laughter have been recorded throughout history, “attempted to classify the variants in these sounds and relate them to the different temperaments, hi hi hi indicating melancholics, he he he cholerics, ha ha ha phlegmatics, and ho ho ho hotheads.”

In his Lives of the Eminent Philosophers, Diogenes Laërtius tells of Socrates’ disciple Aristippus, who “derived pleasure from what was present, and did not toil to procure the enjoyment of something not present.” Such opportunism was not widely admired; Aristippus was sometimes called “the king’s poodle.”

Maurice Sendak, author of classic picture book Where the Wild Things Are, claimed in a 2011 interview never to lie to children. “I refuse to cater to the bullshit of innocence,” he said. He was also in search of a “yummy death,” which he believed could be done “if you’re William Blake and totally crazy.” Two months later, less than a year before he died, Sendak returned to the topic. “I’m a happy old man,” he said. “But I will cry my way all the way to the grave.”

When journalist Peter Andrey Smith attended the 2017 World Happiness Summit in Miami, he asked everyone he met, “Who’s the happiest person here?” Many, he reported, pointed to themselves and said, “Me.”

The Hindu Laws of Manu advises a ruler to act so that “his subjects thrill with joy in him as human beings do at the sight of the full moon.” In ancient times a king secured justice with the help of a divine Rod of Punishment. “Properly wielded,” the text explains, the rod “makes all the subjects happy; but inflicted without due consideration, it destroys everything.”

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.

Even before Jeremy Bentham wrote his own treatise on utilitarianism, Enlightenment scholars were attempting to quantify a happy life. In the eighteenth century, Glasgow professor Francis Hutcheson offered an equation for benevolence, defined as the desire to spread happiness to others, where b = benevolence, a = ability, s = self-love, i = interest, and m = moment of good. His formula: ba = m + sa = m + i, and therefore b = (m + i)/a.

Chinese Taoist philosophers Zhuangzi and Hui Shi took a walk on a bridge over the Hao River in the fourth century bc. “The minnows swim about so freely,” said Zhuangzi; “such is the happiness of fish.” Hui Shi responded, “You are not a fish, so whence do you know the happiness of fish?” “You are not I,” Zhuangzi replied, “so whence do you know I don’t know the happiness of fish?”

“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.”