Born in Frankfurt am Main he studied cello, piano, organ, the trumpet, and composition at the University of Frankfurt. He held positions in Freiburg, Darmstadt, and Prague, before moving to the United States in 1940. He served on the conducting staff of the Metropolitan Opera between 1946 and 1958, when he became music director of the Cincinnati Symphony Orchestra for 13 years. During this period he became a noted orchestra builder and teacher, serving on the staff of the Tanglewood Institute. He wrote The Grammar of Conducting, the most widely used text for orchestral conducting.
After his tenure in Cincinnati, he served as conductor of the Dallas Symphony for a season (1973-74), artistic advisor of the New Jersey Symphony (1976-77), as well as regular engagements with major American orchestras and opera houses. In between this time, he was head of the opera and conducting department at the Curtis Institute of Music (1970-73 and 1983-89). perhaps this is was he is best remembered for, since many of the leading conductors of this day studied under him.