Lewis Gerstel Mack (May 21, 1894 - February 15, 1983) was the author of a history of the Panama Canal and a biography of Paul Cezanne. William Alexander Percy had three prominent gay friends, the art historian Gerstle Mack, who popularized Picasso in America; Harry Stack Sullivan, a prominent psychiatrist; and Huger Jervey, professor of international law at Columbia. Indeed, with Jervey, William Alexander Percy bought Brinkwood, a summer house in MountEagle, Tennessee, near Sewanee.

Mack was born in San Francisco on May 21, 1894, the son of Adolph Mack and Clara Mack. He studied architecture at UC-Berkeley before switching to MIT where he earned a bachelor’s degree in 1916. From 1916 to 1926 he was a draftsman with architectural firms in New York and San Francisco. He served in both World Wars, including 18 months in London as a member of the Office of Strategic Services. After serving in the WWI in Paris as a Lieutenant in the US Reserve Corps of Engineers, he returned to San Francisco to do architectural work and theater design production. In 1926 he left his architecture work to travel to Spain where he made architectural measurements and produced a book on southern Spanish architecture in 1928. A companion volume for northern Spanish architecture appeared in 1930.

Mack did extensive archival research in France, England and the United States on Paul Cézanne before publishing a highly praised biography of the painter in 1935. He followed this with a biography of Henri de Toulouse-Lautrec in 1938, which was equally well received. During World War II, Mack served in the military in England with the Office of Strategic Services. The Land Divided, his history of the Panama Canal, was published in 1944 and his biography of Gustave Courbet appeared in 1951. In 1981, he wrote a book on the 1906 San Francisco earthquake and fire, which he personally survived. Manhattan has been Mack’s home since 1938, but he travelled extensively across the world.

Mack died on February 15, 1983, at his home in Manhattan. He was 88 years old.