Many years later Newton recollected for the benefit of Pierre Varignon:

John Chamberlayne certainly had some acquaintance with Newton and had exchanged letters about political affairs with Leibniz since 1710. He was a journalist, proprietor of an annual resembling Whittaker's Almanac, which had been begun by his father. However, it was only at the end of February 1714 that Chamberlayne wrote to Leibniz deploring the dispute between him and Newton, as though he had recently learned of it, and offering his services as a mediator “between two of the greatest Philosophers & Mathematicians of Europe.” Chamberlayne was the first of several aspirant mediators; but would he have waited four months or so before reacting to the message of the Charta Volans that he had passed on to Newton – even if it were the case that Leibniz (who was of course not supposedly the writer of the “flying paper”) had compromised his position by openly posting it to his friends? However this may be, Newton as yet gave no outward sign of its existence; he did not (so far as we can tell) acknowledge its existence before early April 1714, nor did he do so until he and John Keill and many others were aware that Leibniz's replies to the Commercium Epistolicum were appearing in the Continental literary periodicals.

I became interested in the theme of this book while editing Newton's correspondence during the years of his controversy with Leibniz and Leibniz's supporters. Although the outline of its story has often been told, the great richness of materials bearing upon it that has appeared during recent years made a more detailed study seem worthwhile, and more than one scholar has asked that it should be made. Moreover, a historian of today can approach the calculus dispute with a more detached perspective than his Victorian predecessors could do. He will not be shocked to discover that even Leibniz and Newton could display human faults. Again, the historian who (like myself) has no intention of investigating in technical detail the origins, development, and applications of calculus methods in mathematics can safely rely on modern work devoted to precisely these questions. Although he will not overlook his debt to the pioneers, notably C. I. Gerhardt, he must be particularly grateful for the interpretations and especially the documentation provided by J. E. Hofmann, H. W. Turnbull, and D. T. Whiteside, not to mention other equally reliable scholars who have examined the lesser mathematicians contemporary with Leibniz, James Gregory, and Newton.

Newton'sSecond Letter was retained in London for lack of a safe means of conveyance until May 1677 and only came to Leibniz's hands in late June, eight months after it was written and about as long after Leibniz had settled in Hanover, in the new world where he had to make his career. It was, he acknowledged to Oldenburg, a “truly excellent letter … I am enormously pleased that he has described the path by which he arrived at some of his very elegant theorems.” And he reiterated his praise of Newton's results throughout the letter – no evidence here of a sense that anything had been begrudged him. Before turning to series again, Leibniz took up Newton's brief allusion to the method of tangents, leading on to the anagram (which Leibniz does not mention), and in doing so expressed “publicly” for the first time (unless in informal private communications) his calculus notation; dx, he said, is the difference between two closely related values of any changing quantity x, and dy the corresponding change produced in a second variable y, which is related to x by some mathematical expression. Then if dx is constant, dy will define the slope of the tangent at x.