Beginning in 1932 he studied Greek philology, Semitics, and Assyriology at the University of Basel.
[1] He soon switched to Islamic studies and became a student of the Ottomanist and historian Rudolf Tschudi (1884-1960), under whose supervision he earned his doctorate, with a thesis on the life of the Sufi Abu Ishaq al-Kazaruni.
[2] In 1935 he followed Hellmut Ritter (1892-1971) to Istanbul, where he made his way to academic work.
His writings exerted a great deal of influence on the academic world.
He wrote about the many forms of Islamic mysticism, Islamic manuscripts of the Persian and Arabic languages, the relationship between the Middle East and European cultural history, the history of religion in general, and popular culture.