During the summer of 1940, Cather and Lewis went to Grand Manan for the last time, and Cather finished her final novel, "Sapphira and the Slave Girl", a book much darker in tone and subject matter than her previous works. While Sapphira is understood by readers as lacking a moral sense and failing to evoke empathy, the novel was a great critical and commercial success, with an advance printing of 25,000 copies. It was then adopted by the Book of the Month Club, which bought more than 200,000 copies. Her final story, "The Best Years", intended as a gift for her brother, was retrospective. It contained images or "keepsakes" from each of her twelve published novels and the short stories in "Obscure Destinies".