This fifth volume presents the surviving correspondence from the period of almost four years which is, from a bibliographical point of view, the most important time in Newton's life: with Roger Cotes, Newton revised his Philosophise Naturalis Principia Mathematics and saw it through the press. Considered as a single group of letters, the Newton-Cotes correspondence is the largest and most important section of Newton's scientific correspondence that we have. Nowhere else can one witness Newton in a detailed debate about scientific argument and scientific conclusions - a debate from which he did not always emerge victorious. Nowhere else does Newton write in detail about the text of the Principia. And all scholars agree that this text which was hammered out between Cotes and Newton was the most important of all versions, printed and unprinted; this was (to all intents and purposes) the Principia of subsequent history.

As Newton had by now entered his eighth decade, it can be no surprise that the correspondence in this sixth volume shows a marked decline in his activity and intellectual vigour. While the number of extant letters written by him on other that Mint business is relatively small, the majority of them are devoted to his controversy with Leibniz - Newton's dominant interest during this period. The correspondence of Newton shades gradually into the correspondence of the Newtonians. Thus notably Keill, De Moivre, Chamberlayne, Brook Taylor, the Abbe Conti and Des Maizeaux interested themselves in the calculus dispute, all of them (except the first) having frequent opportunities for personal conversation with Newton.

In this seventh and final volume the letters are divided into two quite distinct groups. The first group begins with the remaining letters of the main chronological sequence written during the closing years of Newton's life, and then proceeds to those few letters to which there is no assignable date with any certainty. The second group of letters, placed in Appendix I, contains corrections and additions to the letters printed in the earlier volumes of the Correspondence. A genealogical table is added to Appendix II to help the reader through the intricacies of Newton's family tree. Even after the creative power of his genius had deserted him, Newton retained to the very end of his long life the characteristic clarity of his thought. Few of Newton's letters in this volume may justly be described as scientific. The relative inactivity of the Mint meant that, although he apparently delegated few of his responsibilities to others, Newton's concerns there were no onerous. Thus it is not surprising that in the last nine years of his life (the period covered in this volume), and particularly from 1725 onwards, there was a decrease in Newton's output of letters; but those which he did write remain as lucid as ever.