Part of the fascination exerted by this thick volume of letters [The Habit of Being] has to do with their evocation of the period which they embrace; much more derives from their revelation of the personality and literary practice of a writer remarkable for the single-mindedness with which she developed and protected a talent that she regarded, quite literally, as God-given. The letters—the first sent from Yaddo to her future agent in 1948, the last a nearly illegible scrawl written six days before her death in 1964—cover her professional career as a writer almost as thoroughly as any biographer might wish. Regrettably, none of the letters written from the years (crucial to her development both as a writer and as a reader) spent at the School for Writers at Iowa State University could be included. Missing also are the letters (presumably of greater personal than literary interest) which...