At last his enemies made it too hot for him at Pisa. He resigned his chair (1591), but only to accept a higher position at Padua, on a salary of one hundred and eighty florins,--not, however, adequate to his support, so that he was obliged to take pupils in mathematics. To show the comparative estimate of that age of science, the fact may be mentioned that the professor of scholastic philosophy in the same university was paid fourteen hundred florins. This was in 1592; and the next year Galileo invented the thermometer, still an imperfect instrument, since air was not perfectly excluded. At this period his reputation seems to have been established as a brilliant lecturer rather than as a great discoverer, or even as a great mathematician; for he was immeasurably behind Kepler, his contemporary, in the power of making abstruse calculations and numerical combinations. In this respect Kepler was inferior only to Copernicus, Newton, and Laplace in our times, or Hipparchus and Ptolemy among the ancients; and it is to him that we owe the discovery of those great laws of planetary motion from which there is no appeal, and which have never been rivalled in importance except those made by Newton himself,--laws which connect the mean distance of the planets from the sun with the times of their revolutions; laws which show that the orbits of planets are elliptical, not circular; and that the areas described by lines drawn from the moving planet to the sun are proportionable to the times employed in the motion. What an infinity of calculation, in the infancy of science--before the invention of logarithms,--was necessary to arrive at these truths!
What fertility of invention was displayed in all his hypotheses;what patience in working them out; what magnanimity in discarding those which were not true! What power of guessing, even to hit upon theories which could be established by elaborate calculations,--all from the primary thought, the grand axiom, which Kepler was the first to propose, that there must be some numerical or geometrical relations among the times, distances, and velocities of the revolving bodies of the solar system! It would seem that although his science was deductive, he invoked the aid of induction also: a great original genius, yet modest like Newton; a man who avoided hostilities, yet given to the most boundless enthusiasm on the subjects to which he devoted his life. How intense his raptures! "Nothing holds me," he writes, on discovering his great laws; "I will indulge in my sacred fury. I will boast of the golden vessels I have stolen from the Egyptians. If you forgive me, I rejoice. If you are angry, it is all the same to me. The die is cast; the book is written,--to be read either now, or by posterity, I care not which. It may well wait a century for a reader, as God has waited six thousand years for an observer."We do not see this sublime repose in the attitude of Galileo,--this falling back on his own conscious greatness, willing to let things take their natural course; but rather, on the other hand, an impatience under contradiction, a vehement scorn of adversaries, and an intellectual arrogance that gave offence, and impeded his career, and injured his fame. No matter how great a man may be, his intellectual pride is always offensive; and when united with sarcasm and mockery it will make bitter enemies, who will pull him down.
Galileo, on his transfer to Padua, began to teach the doctrines of Copernicus,--a much greater genius than he, and yet one who provoked no enmities, although he made the greatest revolution in astronomical knowledge that any man ever made, since he was in no haste to reveal his discoveries, and stated them in a calm and inoffensive way. I doubt if new discoverers in science meet with serious opposition when men themselves are not attacked, and they are made to appeal to calm intelligence, and war is not made on those Scripture texts which seem to controvert them. Even theologians receive science when science is not made to undermine theological declarations, and when the divorce of science from revelation, reason from faith, as two distinct realms, is vigorously insisted upon. Pascal incurred no hostilities for his scientific investigations, nor Newton, nor Laplace. It is only when scientific men sneer at the Bible because its declarations cannot always be harmonized with science that the hostilities of theologians are provoked. And it is only when theologians deny scientific discoveries that seem to conflict with texts of Scripture, that opposition arises among scientific men. It would seem that the doctrines of Copernicus were offensive to churchmen on this narrow ground. It was hard to believe that the earth revolved around the sun, when the opinions of the learned for two thousand years were unanimous that the sun revolved around the earth. Had both theologian and scientist let the Bible alone, there would not have been a bitter war between them. But scientists were accused by theologians of undermining the Bible;and the theologians were accused of stupid obstinacy, and were mercilessly exposed to ridicule.
That was the great error of Galileo. He made fun and sport of the theologians, as Samson did of the Philistines; and the Philistines of Galileo's day cut off his locks and put out his eyes when the Pope put him into their power,--those Dominican inquisitors who made a crusade against human thought. If Galileo had shown more tact and less arrogance, possibly those Dominican doctors might have joined the chorus of universal praise; for they were learned men, although devoted to a bad system, and incapable of seeing truth when their old authorities were ridiculed and set at nought.
Galileo did not deny the Scriptures, but his spirit was mocking;and he seemed to prejudiced people to undermine the truths which were felt to be vital for the preservation of faith in the world.