Restoration of the lecture notes and conversion into book form was undertaken by Caltech physicist David L. Goodstein and archivist Judith R.

You can explain to people who don't know much of the physics, the early history... how Newton discovered... Kepler's Laws, and equal areas, and that means it's toward the sun, and all this stuff.

[2]In a non-course lecture delivered to a freshman physics audience, Feynman undertakes to present an elementary, geometric demonstration of Newton's discovery of the fact that Kepler's first observation, that the planets travel in elliptical orbits, is a necessary consequence of Kepler's other two observations.

In the 1964 lecture, Feynman presents an elementary geometric proof (i.e., in the style of Isaac Newton's 1687 Philosophiæ Naturalis Principia Mathematica) of Kepler's first law.

A proof with ideas similar to Feynman's had already been published by James Clerk Maxwell in his book Matter and Motion (1877).