 From 1925 he was professor of piano at the Cologne Academy of Music but was forced to resign from his post by the Nazis in 1935 and became an 'inner exile', composing almost nothing until after the end of World War II.He joined the Nazi Party in 1937; while not in sympathy with National Socialism, his decision was to avoid government harassment so that he could continue to work, like several other German musicians at the time.This action ruined his post-war reputation, and it did not recover in his lifetime.