One of "The Eight"-a major group in the history of American painting-John Sloan was also an illustrator and cartoonist. Sloan kept an almost daily diary for eight years, for the most part to entertain his first wife, Dolly. Sloan's second wife and widow, Helen Fan Sloan, turned over the diaries and his letters, as well as notes and drawings to Bruce St. John of the Delaware Art Center, which houses the Sloan collection. John Sloan was interested in every social issue that went on around him: the people across the street, the people in the parks, and the policies of his country. He and Dolly...