In the fall of 1927, after a stay of two and a half years in Amsterdam, I accepted the chair of geometry at the University of Vienna and returned to my home town. Formerly the capital of a large, multilingual empire, Vienna emerged from World War I as the head of a small and poor country that had to go through terrible ordeals. But the famine that had begun during the last war years subsided in 1921; tuberculosis, which had been so rampant during that dreadful period that some physicians called it the Viennese disease, receded again; the run-away inflation was stopped in 1923 when 13,000 old crowns were converted into 1 new shilling; and from that time on, Vienna recovered with amazing speed.