Typescript of a lecture given on September 14, 1973, by Curtis Wilson as part of the Formal Lecture Series. The lecture was also published in The College, volume XXXI, number 2 (January 1980), pages 21-31.
Typescript of a lecture given on May 07, 1971 by Curtis Wilson as part of the Formal Lecture Series. (A revised version, originally entitled "Kepler, Newton and Planetary Motion”.)