Career
He concerned himself with opera history, Mozart, and Beethoven. In 1914 he edited the first complete critical edition of the letters of Mozart and his family. After studying musicology in Munich and habilitation as a docent in Marburg he became a professor at the University of Bonn from 1920 to 1945.
As department head for music history he founded the Beethoven Archive at the Beethoven House, Bonn, on 26 March 1927 (the 100th anniversary of Beethoven"s death) and served as its first director until 1945.
He also founded the Institute for Musicology at the University of Bonn – the first such institute at a German school for higher education. He also served on the committee to found the Max Reger Institute which he led until 1953.
After the rise of the Nazi Party, he published his work The complete world view ideas in the Volk"s music of Beethoven in 1934. In the Second World War, he worked for the Reichsleiter Rosenberg Taskforce.