Florence and Padua were in a blaze of excitement. These new discoveries seemed to prove that the earth was not the centre of the universe, but that Copernicus was right when he declared the sun to be the centre. Great opposition began to develop itself. Some of the Aristotelians declared that the telescope of Galileo showed things which do not exist. "It was ridiculous," they said, "that four planets (Jupiter's moons) were chasing each other around a large planet. "It is angels who make Saturn, Jupiter, the sun, etc., turn round. If the earth revolves, it must also have an angel in the centre to set it in motion; but if only devils live there, it would, therefore, be a devil who would impart motion to the earth. "The planets, the sun, the fixed stars, all belong to one species; namely, that of stars--they, therefore, all move, or all stand still. "It seems, therefore, to be a grievous wrong to place the earth, which is a sink of impurity, among the heavenly bodies, which are pure and divine things." Libri, one of the Pisan professors, spoke of the new discoveries as "celestial trifles." When he died, Galileo naïvely remarked, "Libri did not choose to see my celestial trifles while he was on earth; perhaps he will, now he is gone to heaven." Galileo now longed for freedom from teaching, that he might have his time for study and writing. He had planned, he said, "two books on the system of the universe; an immense work (idea, _concetto_), full of philosophy, astronomy, and geometry: three books on local motion, a science entirely new; no one, either ancient or modern, having discovered any of the marvellous accidents which I demonstrate in natural and violent motions; so that I may, with very great reason, call it a new science, discovered by me from its very first principles: three books on mechanics, two on the demonstration of its first principles, and one of problems; and though this is a subject which has already been treated by various writers, yet all which has been written hitherto neither in quantity nor otherwise is the quarter of what I am writing on it. I have also various treatises on natural subjects, on sound and speech, on sight and colors, on the tide, on the composition of continuous quantity, on the motion of animals, and others; besides, I have also an idea of writing some books on the military art, giving not only a model of a soldier, but teaching, with very exact rules, all which it is his duty to know that depends on mathematics; as, for instance, the knowledge of encampment, drawing up battalions, fortifications, assaults, planning, surveying, the knowledge of artillery, the use of various instruments, etc." With all this work in mind, he resigned the professorship at Padua, and removed to Florence, the Grand Duke Cosmo II. giving him a yearly salary of about one thousand dollars, and the title of Philosopher to His Highness.