Paul took over the running of the Cassirer gallery, and supported various Secessionist artists including the sculptors Ernst Barlach and August Gaul, as well as promoting French Impressionism and Post-Impressionism.
Paul asumiu a dirección da galería Cassirer, e apoiou a varios artistas da Secesión, incluíndo os escultores Ernst Barlach e August Gaul, así como á promoción dos impresionistas e posimpresionistas franceses.