Those who dance appear insane to those who cannot hear the music.

First recorded appearance: Germaine de Staël's On Germany (1813). ". . . sometimes even in the habitual course of life, the reality of this world disappears all at once, and we feel ourselves in the middle of its interests as we should at a ball, where we did not hear the music; the dancing that we saw there would appear insane." There are several other pre-Nietzsche examples, indicating that the phrase was widespread in the nineteenth-century; it was referred to in 1927 as an "old proverb".