Man is a rational animal – so at least I have been told. Throughout a long life, I have looked diligently for evidence in favor of this statement, but so far I have not had the good fortune to come across it, though I have searched in many countries spread over three continents.

Often paraphrased as "It has been said that man is a rational animal. All my life I have been searching for evidence which could support this." - Unpopular Essays (1950)