I would like to thank the Council for European Studies, the German Academic Exchange Service, the Getty Grant Program, and Washington University for their generous financial support, without which I would not have been able to complete the research and writing of this book. I would also like to thank Jean Kisling, Liliane Meffre, Klaus Siebenhaar, Hermann Haarmann, the Carl-EinsteinArchiv in Berlin, the Bibliothèque St. Geneviève in Paris, the Galerie Leiris in Paris, and the Getty Research Institute Library in Los Angeles for granting me access to archival materials. I would like to thank the Städtische Galerie im Lenbachhaus in Munich and the Guggenheim Museum in New York for permission to reprint photos of works from their collections. I would like to thank Russell Berman, Ute Berns, Charles Haxthausen, Andreas Huyssen, Klaus Kiefer, Anna Marie Medina, Paul Piccone, and Holmer Steinfath for their comments and criticisms regarding earlier versions of the material in this book. Finally, I would like to thank my wife, Muriel Pan, for her support, insight, criticisms, and patience during the years spent preparing this book for publication.