“To elude boredom man either works harder than is required to satisfy his other needs or he invents play, but he may become tired of play and longs for a third condition which stands in the same relation to play as floating does to dancing and dancing to walking. This third condition is a state of serene agitation; the vision of happiness for the artist and the philosopher.”

—Human, All Too Human: Vol. 1, §611 (edited excerpt).