ranged over the whole field of the intellectual and the imaginative, and produced many works of commanding genius in many different subjects before again buckling down to the more sober tasks of science, which they were doomed to labor upon till now, and quite possibly forever.
Leonardo da Vinci, most versatile of all men, had, to be sure, successfully sought the solution of problems in mechanics, and patiently studied anatomy and, in truth, almost every department of science. But, great as was his insight into the phenomena of matter and motion, and it was perhaps not less than his insight into the fine arts, his work remained without effect, because unknown.
Before Galileo there are but two modern men of science whose importance is capital, Copernicus and Vesalius. The work of Copernicus,[1] though destined finally to tear a veil from before the eyes of men, did not amount to a proof of the heliocentric hypothesis, nor was it at once profoundly influential upon thought. As for Vesalius, he labored upon human anatomy, a subject which has never exerted a wide influence upon the large affairs of civilization. The number of men who, in the sixteenth century and even before, pursued natural science with industry was considerable. But tradition, belief in authority, and the superstitions of the pseudo-sciences of astrology and alchemy, long and successfully resisted the advance of knowledge. Time-honored ideas, nevertheless, had received a rude shock at the hands of Copernicus, and by the year 1600, when Giordano Bruno was burned at the stake, the far-spreading influence of the heliocentric hypothesis, both in its direct hearing, and as an illustration of the power of the untrammeled human intellect, was evident to most thoughtful men.
There followed in the next century such a revolution in thought as has seldom occurred in the whole course of history. To this many factors contributed; the commanding genius of a few great men, Newton, Galileo, Harvey,[2] Kepler, Huygens, Descartes,[3] Bacon,[4] Leibnitz; the growth of algebra, which made possible the invention of analytical geometry by Descartes, and the calculus by Newton and later independently by Leibnitz; the inventions of the telescope and
