Niels Bohr, the Danish physicist and contemporary of Albert Einstein, was instrumental in unearthing the secrets of the atom. His creative thought processes in establishing the important and influential principle of complementarity are studied in this paper. Rothenberg contends that the process of Janusian thinking is central not only to Bohr's discovery, but also to the creative process in general. He reports conducting more than 1700 hours of research interviews with sixty Nobel and Pulitzer