In 1959 Kaplan saw Hal Holbrook's celebrated stage performance of Mark Twain, causing him to become fascinated with Twain, reading everything he could by and about him then writing a 10-page proposal complete with his own contract, which was accepted by Simon & Schuster complete with a $4,000 advance, causing him to leave publishing for writing, despite the anxiety caused by leaving a well-paying job for the uncertainty of a writer's life. Needing distance from the "adrenaline-intoxicated style" of New York, and needing access to Harvard's Widener Library, he and Anne moved to Massachusetts, where he remained for the rest of his life, living in Cambridge, Massachusetts in a 16-room house on Francis Avenue, where "Anne and Joe" became the center of a literary social circle at the heart of 02138, the Harvard Square ZIP code, with neighbors including French chef Julia Child and Harvard economist John Kenneth Galbraith. Said novelist James Carroll: "If there's a writer's community in Boston, they established it. There was a period of about 15 years when their house was the center of the writing life in Boston. Joe was the pillar, and Anne was the flame. Between the two of them they made a big difference in the life of the city."