A unique survey of various aspects of atomic physics, based on a comparative analysis of the hydrogen atom with multi-electron atoms. One of the book's central themes is the concept of degeneracy (both classical and quantal), its origins, and its consequences. Includes a complete chapter on the separability of the Schroedinger equation in parabolic coordinates (i. e. , not restricted to spherical coordinates). The book is also distinguished by its focus on the currently "hot" topic of coherent states.