This third volume covers the period from December 1688 to August 1694. In January 1688/9 Newton was elected one of the representatives of the University of Cambridge in the Convention Parliament, and much of his time was taken up in dealing with his new responsibilities, as may be gathered from his correspondence with Covel, Vice-Chancellor of the University. The letters in question, which were printed in collected form in 1848, provide a picture of the unsettled period which followed the flight of King James II to the court of Louis XIV, and the landing of William, Prince of Orange, on...

This first volume is particularly rich in matters of concern to the historian of science. It shows the young Newton in the plenitude of his powers; he himself wrote of the period at Woolsthorpe, which ended before any surviving letters of real consequence were written, 'for in those days I was in the prime of my age for invention, and minded Mathematics and Philosophy more than at any time since'. The main scientific topics with which these letters deal are the reflecting telescope; the early mathematical work; and the fundamental work on the decomposition of white light by the prism.

This second volume contains the first exchange of letters between Newton and Leibniz, which took place through the intermediacy of Oldenburg, as well as the beginning of Newton's correspondence of Flamsteed, which resulted from their common interest in the comet of 1680. Of prime interest is the correspondence with Halley, whose compelling zeal and energy played such a part in persuading Newton to write the Principia. This great work was published about midsummer 1687. As early as New Year 1684/5 it was known in some quarters that Newton was busying himself with applying his laws of motion to...