“May 21, 1994, Melody Maker.”

Introduction
The Open Society and Its Enemies (1945)

Mekubolim, 1906. Alle Verk, vi. 53.
Context: There are melodies that must have words... and melodies that sing themselves without words. The latter are of a higher grade. But these, too, depend on a voice and lips,... hence are not yet altogether pure, not yet genuine spirit. Genuine melody sings itself without a voice. It sings inside, within the heart, in man's very entrails!

This is Your Brain on Music (2006)

Interview with Einstein (1930)

The Kasîdah of Hâjî Abdû El-Yezdî (1870)
Context: Is not the highest honour his who from the worst hath drawn the best;
May not your Maker make the world from matter, an it suit His hest? Nay more, the sordider the stuff the cunninger the workman's hand:
Cease, then, your own Almighty Power to bind, to bound, to understand.

Extract from Prison Diaries, published in The Guardian, 2006
Music and politics

Source: A Wild Sheep Chase: A Novel (1982)

Melodia semplice e varietà nel ritmo.
His motto for Italian music, formulated in a letter to Filippo Filippi, August 26, 1868; Luca Somigli Legitimizing the Artist (2003) p. 103.
Often misquoted as "Simple melody – clear rhythm!"