The unusual ambition of this volume is to engage scientists, historians, and philosophers in a common quest to delineate the structure of the creative thinking responsible for major advances in physical theory. The topic does not fit anyone discipline's proprietary interests, and can only be pursued cooperatively. This volume was conceived in the hope that the importance of learning something general about how theories are developed and what makes the difference between productive and abortive directions of theo- retical inquiry could overcome well-known barriers to such cooperation. The...