Physics is very muddled again at the moment; it is much too hard for me anyway, and I wish I were a movie comedian or something like that and had never heard anything about physics.

Letter to R. Kronig, 21 May 1925, quoted in R. Kronig, 'The Turning Point', in M. Fierz and V. F. Weisskopf (eds.), Theoretical Physics in the Twentieth Century. A Memorial Volume to Wolfgang Pauli (1960). Trans. in M. Klein, Letters on Wave Mechanics, x