Gustave Flaubert wrote to his mistress, Louise Colet: "An author in his book must be like God in the universe, present everywhere and visible nowhere." In his books, Flaubert sought to observe that principle; but in his many impassioned letters he allowed his feelings to overflow, revealing himself in all of his human complexity. Sensuous, witty, exalted, ironic, grave, analytical, the letters illustrate the artist's life--and they trumpet his...