American art historian. He was born in Moscow, grew up in Berlin, settled in England in 1933, and emigrated to the USA in 1945. After several years as a freelance writer and teacher of drawing, he turned to art history and gained a PhD from the Institute of Fine Arts, New York University, in 1960. He was subsequently a professor of art history at Hunter College, City University of New York, then moved to the University of Pennsylvania in 1975. His learned, stimulating, and sometimes provocative writings have ranged from the Renaissance to contemporary art. A collection of his pieces on modern art was published in 1972 as Other Criteria: Confrontations with Twentieth-Century Art. The title essay is a key document in the reaction against the formalist writing of Clement Greenberg. There are also three essays on Picasso, whose late work he was among the first to accord serious treatment, and an influential account of the work of Jasper Johns. This was unusual at the time in its honesty in describing the difficulties of confronting challenging new art, although its account of the false starts and confusions involved have now become something of a cliché of art criticism. See also avant-garde.