"Orson Wells made Citizen Kane, his greatest movie, when he was 25 years old; Frank Lloyd Wright designed Fallingwater, his most famous house, when he was 70. Contrasts as great as this raise the question of whether there is a general explanation of when in their lives great innovators are most...

Two great movie directors were both born in 1930. One of them, Jean-Luc Godard, revolutionized filmmaking during his 30s, and declined in creativity thereafter. In contrast, Clint Eastwood did not direct his first movie until he had passed the age of 40, and did not emerge as an important...