Sybil Gordon Kantor’s book is an important contribution to the historiography of twentieth-century American art: It is intellectual and biographical history at its most rigorous. Kantor has scoured archives and primary sources to tell a story of the emergence of modernism in the U.S. through one man who was nevertheless the product of other men and women who had influenced him through their ideas, collections, and personal contacts. As today’s critics and historians bid farewell...