"I put most of myself into that opus," Edith Wharton said of <I>The Reef,</I> possibly her most autobiographical novel. Published in 1912, it was, Bernard Berenson told Henry Adams, "better than any previous work excepting <I>Ethan Frome."</I> <P> A challenge to the moral climate of the day, <I>The Reef</I> follows the fancies of George Darrow, a young diplomat en route from London to France, intent on proposing to the widowed Anna Leath. Unsettled by Anna's reticence, Darrow drifts into an affair with Sophy Viner, a charmingly naive and impecunious young woman whose relations with Darrow and Anna's family threaten his prospects for success. <P> For its dramatic construction and acute insight into social mores and the multifaceted problem of sexuality, <I>The Reef</I> stands as one of Edith Wharton's most daring works of fiction.