This collection was gifted to the Sterling and Francine Clark Art Institute Library in 2012 by Peter Guille Jr. The collection includes correspondence and diary entries of Robert Sterling Clark as well as the Supreme Court Case of NY complaint dated January 14, 1927 and answer dated May 16, 1927 of Robert Sterling Clark against his brothers. The correspondence letters are between art dealers, horse breeders, and business associates between 1941 and 1943. The diary entries are from 1945 to 1948 with one entry dated from 1941. Entries recount friendships; disputes; meals and cooking; parties; financial investments; the purchase of artwork and silver; his relationship with various art dealers; his thoughts and opinions about art and collecting; horse breeding and racing; politics; and the other subjects that make up a lifetime.