one year; and his life was one of such close and continued mental application as has hardly a parallel in its intensity, any more than in its results. This was his fruiting-time, in which were given to the world, as far as Newton ever did give to the world, his discoveries, mathematical, optical, and dynamical, including the method of fluxions, the laws of light, and his improvements of the reflecting telescope-the firstfruit of which, the instrument constructed with his own hands, was presented to the Royal Society immediately after his election as a fellow, on January 11, 1671-2, and was followed by the account of his pregnant researches into the decomposition of light, and his crowning discovery, the law of universal gravitation.

The germs of all these solutions of Nature's mysteries seem to have shaped themselves during that memorable year when, driven by the plague from Cambridge, he retreated to the quiet seclusion of Woolthorpe. Here it was that to the new-made Bachelor of Arts, sitting in the orchard in the autumn of 1665, was revealed, in musing on the fall of the apple, the conception of the force that keeps the planets in their orbits. Here

it was that, the same year, in using the prismthe purchase of which is recorded in one of his little books of expenses for 1664-he penetrated to his first apprehension-still imperfect-of the laws of light and the nature of colours. It was here that he applied himself to the grinding of optic glasses, and wrought out his method of fluxions; his work on which, in his quiet rooms at Trinity, had been interrupted by the outbreak of the plague. And even by this time he may have turned his mind to the more darkling regions of inquiry and experiment which form the debatable ground between chemistry and alchemy, in which he was so deeply absorbed at several later periods of his life.

But it is in his middle age, between thirty and fifty, that we see Newton as the revealer of Nature's laws; using the Royal Society as his medium, but slow to utter himself, and never committing his discoveries to paper in a form intelligible to others except on compulsion, and then so impatient of controversy, and averse to personal discussion, that he seems to regret that ever he had been induced to break the silence of his thought, and carry the light beyond his solitary