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.