Hans Keller (1919–1985) was one of the most brilliant and stimulating writers on music of his day, and this is the first large selection of his essays. His work draws on his rich and diverse experience as a string-player, composer, teacher, analyst and critic, and also reflects a deep interest in psychoanalysis. The first part of the book addresses psychological issues relating to critics, listeners, players and composers; the second analyses music by a wide range of composers from Haydn to the present day; and the third propounds his new theory of music, with essays on unity and contrast, motifs, themes, keys, timbre and rhythm. There is also a 'wordless functional analysis' of a Mozart piano sonata published here for the first time. The volume concludes with a magisterial account of what Keller deemed to be 'the principles of composition'.