Margaret Cavendish (1623-1673), Duchess of Newcastle and one of the best-known women writers of the her time, is enjoying a revival in the wake of Aphra Behn's canonization: She appears in the Norton Anthology of English Literature, her poetry will appear in a new edition, and Penguin has recently reprinted her science-fiction novel The Blazing World . This is an edition of her hilarious and rowdy letters, unavailable since their original publication...