  The second segment of the “Copernican Scholium” addresses an issue in orbital astronomy that forms a still further component in the historical context of the Principia. Separate from the question whether Kepler's or some other approach was to be preferred was the question whether the true motions are significantly more irregular and complicated than the calculated motions in any of these approaches. The complexity of the lunar orbit and the continuing failure to describe it within the accuracy Kepler had achieved for the planets was one consideration lying behind this question. Another came from Kepler's own finding, noted in the Preface to his  Rudolphine Tables[9] and subsequently supported by others, that the true motions may involve further vagaries, as evidenced by apparent changes in the values of orbital elements over time. The most important consideration behind this question, however, came from Descartes' claim that, in keeping with the changing motions of his vortices over long periods of time, the orbits are not mathematically perfect and “they are continuously changed by the passing of the ages” [D, 3, 34]. In the second segment of the quoted Scholium, Newton concludes that, in contrast to the ellipse that answered the mathematical question put to him by Hooke and Halley, the true orbits are not ellipses, but are indeed indefinitely complex. This conclusion is nowhere so forcefully stated in the published Principia, but knowledgeable readers nonetheless saw the work as answering the question whether the true motions are mathematically perfect in the negative.