Although much has been published about the effects of Newton's dynamics, until recently, only a physics specialist could access the intricacies of Newton's solution.

The remarkably straightforward theoretical framework that underlies the calculation of the force required to sustain ideal planetary motion is well explained in The Key to Newton's Dynamics. J. Bruce Brackenridge places the issue in a philosophical and historical context while highlighting the physicist's obligation to both Descartes and Galileo.

He follows the development of Newton's work on the Kepler problem from its inception at Cambridge prior to 1669, through a resurgence of interest ten years later, to its culmination in the first three sections of the Principia.

This work covers a significant gap in the literature and is clear and significant. Unquestionably, Brackenridge is the kind of talented, understanding instructor one would expect from a reputable liberal arts college.