The analysis is static, based on the third edition.

Although Harper mentions many of the alterations, he does not query the reasons for these changes. The Principia went through three editions, and the relevant portions of Book III saw significant revisions over a span of forty years. However, though it is extensively researched and filled with a wealth of historical detail, it will not set a new standard for Newton scholarship in the stricter sense, for it fails to contextualize its subject. This is a serious and learned work that will set a standard for future philosophical analyses of Newton's argument for universal gravitation. Harper's book focuses on the first half of this project, giving for the most part a running commentary with appendices on the first thirteen propositions of Book III and their corollaries, together with the three laws of motion.

In the preface to the first edition of Philosophiae Naturalis Principia Mathematica, Newton writes, 'For the whole difficulty of philosophy appears to be to discover the forces of nature from the phenomena and then to demonstrate the other phenomena from these forces.' This program, for at least one force, is carried out in Book III of the Principia wherein Newton claims to establish the law of universal gravity primarily from Keplerian features of planetary and lunar motion and then to derive from this force the tides, the shape of the earth, the precession of the equinoxes, lunar anomalies and other phenomena.

The title and dust jacket portrait of Newton eliciting the celebrated phenomenon of colors may lead one to think this is a comprehensive work on Newton's scientific method, including his experimental work in optics.

Isaac newton gravity