Why do we, you and I and many another, protest so vehemently against war, instead of just accepting it as another of life's odious importunities? For it seems a natural enough thing, biologically sound and practically unavoidable.

letter in 1931 to Albert Einstein, who had invited him to be one of 'an association of intellectuals' actively opposed to war; Otto Nathan and Heinz Norden (eds.) Einstein on Peace (1960)