A remarkable personal and professional chronicle by one of today's leading physicists, this is a collection of Chen Ning Yang's personally selected papers supplemented by his insightful commentaries. Including previously unpublished or hard-to-find works, this volume contains Yang's important papers on statistical physics, nuclear forces, and particle physics. Among them are his seminal work with T D Lee on the nonconservation of parity, for which they won the Nobel Prize, and his work with R L Mills, which led to modern gauge theories with their exciting prospects for the broad unification of field theories. The commentaries were written especially for this volume and provide a fascinating account of Yang's development as a physicist as well as a look at many important physicists of the 20th century. They trace the development of Yang's interests and ideas from his graduate school days to the present, showing how he worked with his colleagues and how their physics came into being. Together, the papers and commentaries in this unique collection comprise a powerful personal statement, shedding light on both the intellectual development of a great physicist and on the nature of scientific inquiry.