Clark's involvement in founding of the discipline of non-solar x-ray astronomy. Factors, philosophical, theoretical and experimental, that led to the discovery of the first non-solar x-ray source in 1962. Relationship with colleagues at the Massachusetts Institute of Technology (MIT) and American Science and Engineering, Inc.; backgrounds of scientists who entered x-ray astronomy. Also prominently mentioned are: Martin Annis, Riccardo Giacconi, Nancy Grace Roman, Bruno Benedetto Rossi; American Science and Engineering, Inc., and Scorpio X-1 (Rocket).