and of the new doctrine of "prerogative instances," or crucial observations and experiments in the work of discovery. In short, Bacon's entire achievement in science is a plan for an impossible universe of knowledge. As far as he attempted to advance particular sciences by applying his method to their detailed phenomena, he wrought with imperfect knowledge of what had been done, and with cumbrous and usually misdirected efforts to fill the gaps he recognized. In a few instances, by what seems an almost superhuman instinct for truth, rather than the laborious process of investigation which he taught, he anticipated brilliant discoveries of later centuries. For example, he clearly pointed out the necessity of regarding heat as a form of motion in the molecules of matter, and thus foreshadowed, without any conception of the means of proving it, that which, for investigators of the nineteenth century, has proved the most direct way to the secrets of nature. But the testimony of the great teachers of science is unanimous, that Bacon was not a skilled observer of phenomena, nor a discoverer of scientific inductions; that he contributed no important new truth, in the sense of an established law, to any department of knowledge; and that his method of research and reasoning is not, in its essential features, that which is fruitfully pursued by them in extending the boundaries of science, nor was his mind wholly purged of those "idols of the cave," or forms of personal bias, whose varying forms as hindrances to the "dry light" of sound reason he was the first to expose. He never appreciated the mathematics as the basis of physics, but valued their elements mainly as a mental discipline. Astronomy meant little to him, since he failed to connect it directly with human well-being and improvement; to the system of Copernicus, the beginning of our insight into the heavens, he was hostile, or at least indifferent; and the splendid discoveries successively made by Tycho Brahe, Galileo, and Kepler, and brought to his ears while the 'Great Instauration' filled his mind and heart, met with but a feeble welcome with him, or none. Why is it, then, that Bacon's is the foremost name in the history of English, and perhaps, as many insist, of all modern thought? Why is it that "the Baconian philosophy" is another phrase, in all the languages of Europe, for that splendid development of the study and knowledge of the visible universe which since his time has changed the life of mankind?