In January 1902, the German art dealer Paul Cassirer, a major proponent of Berlin Secession artists, as well as the conduit through which French Impressionism and Post-Impressionism gained currency in Germany, presented a show at his Berlin gallery (Galerie Paul Cassirer) in which he juxtaposed two highly original yet antithetical artists. Both artists were rather unknown at the time, but one-half of this visionary curatorial diptych would become a household name, instantly recognizable for his...