The inspired moment may sometimes be described as a kind of hallucinatory state of mind: one half of the personality emotes and dictates while the other half listens and notates. The half that listens has better look the other way, had better simulate a half attention only, for the half that dictates is easily disgruntled and avenges itself for too close inspection by fading entirely away.

Music and Imagination (ed. Harvard University Press, 1980) - ISBN: 9780674589155