Mathematician, born in Elmshorn, Germany. He studied at Göttingen under David Hilbert, and became professor at Zürich (1913) and Göttingen (1930). Refusing to stay in Nazi Germany, he went to Princeton in 1933. He made important contributions to the theory of Riemann surfaces, the representation theory of Lie groups, the mathematical foundations of relativity and quantum mechanics, and the philosophy of mathematics. His book Symmetry (1952) is a largely non-technical account of the relation between group theory and symmetry in pattern and design.