 This encounter, mediated by painter Max Bergmann, may have helped to radicalize Duchamp's vision on art.Later in the 1910s, Bloch and Vorel were close friends; they visited each other's studios and drew portraits of one other.Although Vorel ultimately refused to join any particular group of artists, his work shares common traits with that of several German Expressionists—including George Grosz and Oskar Kokoschka.