[American Modernist] Cowell, Henry. (1897 - 1965) 1928 "What is Proletarian Music?" Lecture InvitationPrinted 5. 5 x 3. 5 inch promotional postcard for a lecture by Henry Cowell titled "What is Proletarian Music?" at the Ruthenberg House Auditorium of the Worker's School, 121 Haight Street [San Francisco, 1928]. A touch of subtle toning and tiny tear to bottom edge, otherwise fine, clean condition. Cowell, like many of musical and artistic colleagues, took a keen interest in social welfare, and in particular the relationship between the arts and