When Apple released its Shuffle feature for iPods, users were deceived by the true randomness of its playback; songs from the same album or artist were often grouped by chance. Complaints led Steve Jobs to alter the device’s programming and begin offering Smart Shuffle, which allowed users to adjust the likelihood of hearing similar songs in a row. “We’re making it less random,” he said, “to make it feel more random.”

“The contempt of risk and the presumptuous hope of success are in no period of life more active than at the age at which young people choose their professions,” wrote Adam Smith in 1776. “How little the fear of misfortune is then capable of balancing the hope of good luck.”

A 2011 study found that Chinese consumers are charged more due to “superstitious manipulations” of retail prices—fives and sixes appear more often than unlucky fours, eights and nines more than unlucky sevens. “Retailers,” the study reported, “are the clear winners.”

In Serbian oral tradition, fate often appears written on foreheads. A typical story tells of a man on the run from a plague personified as a woman. “It is not fated that I should kill you,” she says on catching him and seeing his forehead’s inscription. “You’ll be killed by a turtle.” Later, the man mows a field. His scythe hits a turtle, ricochets off its shell, and slices his leg. He dies soon after from blood poisoning.

“Among the greatest pieces of luck for high achievement is ordeal,” poet John Berryman told an interviewer in 1970, two years before his death. “Certain great artists can make out without it, Titian and others, but mostly you need ordeal. My idea is this: the artist is extremely lucky who is presented with the worst possible ordeal which will not actually kill him. At that point, he’s in business.”

“The die,” wrote geographer Pausanias circa 150, “is the plaything of youths and maidens, who have nothing of the ugliness of old age.”