New York Dada known and controversial across the New York, as well as American in general, art scene. His personality was equally intoxicating as his art; according to Richter, "Duchamp's attitude is that life is a melancholy joke, an indecipherable non-sense, not worth the trouble of investigating. To his superior intelligence the total absurdity of life, the contingent nature of a world denuded of all values, are logical consequences of Descartes' Cogito ergo sum." Most famous amongst the works created by Duchamp in the New York period were his ready-mades, particularly the piece entitled "Fountain". During his time in New York he maintained
Cogito, ergo sum ("If I am mistaken, I am") (book XI, 26), and also anticipates modern refutations of the concept. Furthermore, in the "Enchiridion" Augustine attempts to refute skepticism by stating, "[B]y not positively affirming that they are alive, the skeptics ward off the appearance of error in themselves, yet they do make errors simply by showing themselves alive; one cannot err who is not alive. That we live is therefore not only true, but it is altogether certain as well" (Chapter 7 section 20). In 1640 correspondence, Descartes thanked two colleagues for drawing his attention to Augustine and notes similarity and difference.