A masterful treatment of quantum theory, this classic work develops the subject's most important concepts from experimental evidence and from theory related to the wave nature of free particles. The first half shows how the classical mechanics of point particles can be generalized into a consistent quantum mechanics; the second part deals with extensions of quantum theory needed for problems of atomic and molecular structure. Suitable for advanced undergraduates and graduate students in physics as well as historians of modern science, this universally praised translation will be a valuable addition to any physical science library.