Gertrude Stein, who lived and wrote as though she knew she would be legendary, is more than that now: she is an icon. The image of Stein, sitting under the Picasso portrait of her in the living room at 27, rue de Fleurus, in Paris, has permanently entered the consciousness of literate people everywhere. The image carries with it a myriad of associations: the brilliant hostess around whom gathered a dazzling array of avantgarde writers and artists--among them Ernest Hemingway, F. Scott Fitzgerald, Pablo Picasso, Henri Matisse, Sherwood Anderson, Alfred Steiglitz, Carl Van Vechten, Guillaume Apollinaire, Georges Braque, Marie Laurencin, Robert Delaunay; the powerful personality, alternately brusque or charming as the situation or her mood dictated; the dominant half of a famous and apparently harmonious lesbian relationship with Alice B. Toklas, with whom she lived for thirty-seven years; the originator of the phrase, "A rose is a rose is...