My earliest intellectual contact with the work of Nancy Schwartz dates from my graduate-student days at Minnesota. There was an optimal growth course, taught by John Chipman, that was not to be missed. The pièce de résistance was Pontryagin's Maximum Principle, and I will always be thankful to the Journal of Economic Theory article by Kamien and Schwartz for helping me to get through it. It took several nights of a still-remembered week, but at the end I understood the principle. So I have a debt that is a pleasure to repay on this occasion. It is for me truly an honor to be delivering the Nancy L. Schwartz Memorial Lecture. My subject will be market competition as viewed by traditional general equilibrium theory. Nancy Schwartz made outstanding contributions to our understanding of dynamic market competition from the standpoint of industrial organization theory. I hope, therefore, that this is a fitting topic for me in this lecture.