thought. They found acceptance in England and France, and have been revived in later times in the systems of Baader and Schelling.
7. The Foundation of Modern Physics.
In no field has the modern period so completely broken with tradition as in physics. The correctness of the Copernican theory is proved by Kepler's laws of planetary movement, and Galileo's telescopical observations; the scientific theory of motion is created by Galileo's laws of projectiles, falling bodies, and the pendulum; astronomy and mechanics form the entrance to exact physics—Descartes ventures an attempt at a comprehensive mechanical explanation of nature. And thus an entirely new movement is at hand. Forerunners, it is true, had not been lacking. Roger Bacon (1214-94) had already sought to obtain an empirical knowledge of nature based upon mathematics; and the great painter Leonardo da Vinci (1452-1519) had discovered the principles of mechanics, though without gaining much influence over the work of his contemporaries. It was reserved for the triple star which has been mentioned to overthrow Scholasticism. The conceptions with which the Scholastic-Aristotelian philosophy of nature sought to get at phenomena—substantial forms, properties, qualitative change—are thrown aside; their place is taken by matter, forces working under law, rearrangement of parts. The inquiry into final causes is rejected as an anthropomorphosis of natural events, and deduction from efficient causes is alone accepted as scientific explanation. Size, shape, number, motion, and law are the only and the sufficient principles of explanation. For magnitudes alone are knowable; wherever it is impossible to measure and count, to determine force mathematically, there rigorous, exact science ceases. Nature a system of regularly moved particles of mass; all that takes place mechanical movement, viz., the combination, separation, dislocation, oscillation of bodies and corpuscles; mathematics the organon of natural science! Into this circle of modern scientific categories are articulated, further, Galileo's new conception of motion and
