Niels Bohr ranks with Einstein among the physicists of the 20th century. He rose to this status through his invention of the quantum theory of the atom and his leadership in its defense and development. This book presents unpublished excerpts from extensive correspondence between Niels Bohr and his immediate family, and uses it to describe and analyze the psychological and cultural background to his invention. It also contains a reprinting of the three papers of
1913 (the Trilogy in which Bohr worked out the provisional basis of his theory.