Genius, anti-artist, charlatan, guru, imposter? Since 1914 Marcel Duchamp has been called all these. Arousing passion and controversy, he has exerted a great influence on art, whose very nature he challenged and redefined as concept rather than product by questioning its traditionally privileged optical nature. At the same time, he never ceased to be engaged, openly or secretly, in provocative and enigmatic activities and works which transformed traditional artmaking procedures. This monograph, written with the support of Duchamp's widow, challenges received ideas, misunderstanding and misinformation.