[Illustration: FIG. 115. GALILEO GALILEI (1564-1642)]
Finally an Italian, Galileo Galilei, a professor at the University of Pisa, developing a telescope that would magnify to eight diameters, discovered Jupiter's satellites and Saturn's rings. The story of his discovery of the satellites of Jupiter is another interesting illustration of the careful scientific reasoning of these early workers (R. 206). Galileo also made a number of discoveries in physics, through the use of new scientific methods, which completely upset the teachings of the Aristotelians, and made the most notable advances in mechanics since the days of Archimedes. For his pronounced advocacy of the Copernican theory he was called to Rome (1615) by the Cardinals of the Inquisition, the Copernican theory was condemned as "absurd in philosophy" and as "expressly contrary to Holy Scripture," and Galileo was compelled to recant (1616) his error. [9] For daring later (1632) to assume that he might, under a new Pope, defend the Copernican theory, even in an indirect manner, he was again called before the inquisitorial body, compelled to recant and abjure his errors (R. 207) to escape the stake, and was then virtually made a prisoner of the Inquisition for the remainder of his life. So strongly had the forces of medievalism reasserted themselves after the Protestant Revolts!
[Illustration: FIG. 116. SIR ISAAC NEWTON (1642-1727)]
Finally the English scholar Newton (1642-1728), in his Principia (1687), settled permanently all discussions as to the Copernican theory by his wonderful mathematical studies. He demonstrated mathematically the motions of the planets and comets, proved Kepler's laws to be true, explained gravitation and the tides, made clear the nature of light, and reduced dynamics to a science. Of his work a recent writer, Karl Pearson, has said:
The Newtonian laws of motion form the starting point of most modern treatises on dynamics, and it seems to me that physical science, thus started, resembles the mighty genius of an Arabian tale emerging amid metaphysical exhalations from the bottle in which for long centuries it had been corked down.
So far-reaching in its importance was the scientific work of Newton that
Pope's couplet seems exceedingly applicable:
Nature and Nature's laws lay hid in night;
God said, "Let Newton be," and all was light.
THE NEW METHOD APPLIED IN OTHER FIELDS. The new method of study was soon applied to other fields by scholars of the new type, here and there, and always with fruitful results. The Englishman, William Gilbert (1540-1603) published, in 1600, his De Arte Magnetica, and laid the foundations of the modern study of electricity and magnetism. A German-Swiss by the name of Hohenheim, but who Latinized his name to Paracelsus (1493-1541), and who became a professor in the medical faculty at the University of Basle, in 1526 broke with mediaeval traditions by being one of the first university scholars to refuse to lecture in Latin. He ridiculed the medical theories of Hippocrates (p. 197) and Galen (p. 198), and, regarding the human body as a chemical compound, began to treat diseases by the administration of chemicals. A Saxon by the name of Landmann, who also Latinized his name to Agricola (1494-1555), applied chemistry to mining and metallurgy, and a French potter named Bernard Palissy (c. 1500- 88) applied chemistry to pottery and the arts. To Paracelsus, Agricola, and Palissy we are indebted for having laid, in the sixteenth century, the foundations of the study of modern chemistry.
[Illustration: FIG. 117. WILLIAM HARVEY (1578-1657)]
A Belgian by the name of Vesalius (1514-64) was the first modern to dissect the human body, and for so doing was sentenced by the Inquisition to perform a penitential journey to Jerusalem. One of his disciples discovered the valves in the veins and was the teacher of the Englishman, William Harvey, who discovered the circulation of the blood and later (1628) dared to publish the fact to the world. These men established the modern studies of anatomy and physiology. Another early worker was a Swiss by the name of Conrad Gessner (1516-65), who observed and wrote extensively on plants and animals, and who stands as the first naturalist of modern times.