Gertrude Stein, a Vichy supporter? For most people, including those filling the rooms of several recent major museum exhibits on Stein, this news might come as a surprise. A Jewish-American experimental writer, friend of Picasso and muse to Hemingway, Gertrude Stein seems to embody high modernism in its most creative and progressive form. Her patronage of modernism’s giants—Cézanne, Picasso, and Matisse—made her a radical in her day. Her playful and innovative writing seems to antici...