One of the nation's most influential teachers of art history; taught at Williams College from 1936 to 1976, serving as department chairman from 1940 to 1969; retired as Amos Lawrence professor of art; directed the Williams College Museum of Art from 1948 to 1976; from 1954 to 55, was executive secretary of Harvard's Committee on the Visual Arts; his books included Manet (1953), Guide to the Art Museums of New England (1958, greatly enlarged and republished in 1982 as The Art Museums of New England), Art Tours and Detours in New York State (1964), and Handbook to the Williams College Museum of Art; his essays appeared in the New York Times and Saturday Review, and in the early 1950s, regularly wrote art and book reviews for The Nation; served in the Naval Reserve during World War II, attaining the rank of lieutenant commander; was sent to the U.S. Office of Strategic Services in 1945 as a member of the Art Looting Investigation Unit; interrogated Nazi art personnel in Austria and Munich and wrote the official report on the formation of Adolf Hitler's art collection; from 1950 to 1951, the U.S. State Department employed him in Munich as director of the Central Collecting Point, supervising the return of art that had been plundered by Nazis.