Till after the age of fifty, Galileo was allowed to go on undisturbed, or at least not materially disturbed, by opposition in his career of success--observing, learning, theorizing, calculating, explaining, teaching--a prominent figure indeed. Not only did he take a large share in establishing firmly the Copernican system of astronomy, but some of the principal laws of motion were discovered by him. He first found the uses of a pendulum, and there is strong reason for believing that the first microscope, as well as the first telescope, was from his hands. But after the age of fifty, reverses came, and one blow succeeded another. Rome had been gradually waking up to the true sense of all that was implied by his discoveries and his teaching, and at length she let loose her thunders--impotent thunders enough, so far as regarded any permanent checking of the progress of truth, but by no means impotent to crush one defenseless victim, the champion of scientific truth in that country and age. Years of greater or less opposition, amounting often to persecution, were followed by an imperious order commanding him to Rome. There he was examined and severely “questioned,” and recantation was forced from him, worth as much as such forced recantations commonly are worth. Even then he did not cease from the work that he loved; even in prison he carried it on; even when he might not write, nothing could stop him from thinking. But his health was broken; his liberty was taken away; illness followed illness; his favorite daughter died; his eyesight gradually failed; the last book that he wrote might not for a long while be printed; and at last he passed away, mercifully set free from those who, in an essentially bigoted and intolerant age, were incapable of appreciating his greatness. They would fain _then_ have denied him even a respectable grave. Now, all the civilized world unites to honor the name of Galileo. CHAPTER XXXIII. ISAAC NEWTON. Even the great fame of Galileo must be relegated to a second place in comparison with that of the philosopher who first saw the light in a Lincolnshire farmhouse on the 25th of December, 1642, the very same year of Galileo’s death. His father, Isaac Newton, had died before his birth. The little Isaac was at first so frail and weakly that his life was despaired of. The watchful mother, however, tended her delicate child with such success that he ultimately acquired a frame strong enough to outlast the ordinary span of human life.