Galileo Galilei Galileo Galilei From an early age Galileo Galilei manifested his aptitude for mathematical and mechanical pursuits, but his parents, wishing to turn him aside from studies that promised no substantial return, destined him for the medical profession. But all was in vain, and at an early age the youth had to be left to follow the bent of his native genius, which speedily placed him among the most renowned natural philosophers. Galileo’s great achievements are magnified by the fact that, happily combining experiment with calculation, he opposed the prevailing system. This system did not encourage going directly to nature for investigation of her laws and processes, instead it was held that these were best learned from authorities, especially that of Aristotle who was supposed to have spoken the last word upon all such matters. Against such a superstition Galileo resolutely and vehemently set himself.
He not only soon discredited many beliefs that had been accepted as indisputable, but aroused a storm of opposition and indignation amongst those whose opinions he discredited. Galileo was a fierce controversialist, who, not content with refuting adversaries, was bent upon confounding them. Moreover, he wielded an exceedingly able pen, and unsparingly ridiculed and exasperated his opponents. Undoubtedly he thus did much to bring upon himself the troubles for which he is now chiefly remembered. Galileo is most widely remembered for his astronomical discoveries. In this connection, his greatest achievement was undoubtedly his virtual invention of the telescope.
Hearing early in 1609 that a Dutch optician, named Lippershey, had produced an instrument by which the apparent size of remote objects was magnified, Galileo at once realized the principle by which such a result could alone be attained, and, after a single night devoted to consideration of the laws of refraction, he succeeded in constructing a telescope which magnified three times, its magnifying power being soon increased to thirty-two. This instrument being provided and turned towards the heavens, the discoveries, which have made Galileo famous, were bound at once to follow, though undoubtedly he was quick to grasp their full significance. The moon was shown not to be, as the old astronomy taught, a smooth and perfect sphere, of different nature to the earth, but to possess hills and valleys and other features resembling those of our own globe. The planet Jupiter was found to have satellites, thus displaying a solar system in miniature, and supporting the doctrine of Copernicus. It had been argued against the said system that, if it were true, the inferior planets, Venus and Mercury, between the earth and the sun, should in the course of their revolution exhibit phases like those of the moon. Since these were invisible to the naked eye, Copernicus had to advance the quite erroneous explanation that these planets were transparent and the sun’s rays passed through them.
But with his telescope Galileo found that Venus did actually exhibit the desired phases, and the objection was thus turned into an argument for Copernicanism. Finally, the spots on the sun, which Galileo soon perceived, served to prove the rotation of that luminary, and that it was not incorruptible as had been assumed. Upon obtaining this proof, Galileo, profoundly assured of the truth of his cause, set himself with his habitual vehemence to convince others, and so helped to create the troubles that greatly embittered the latter part of his life. At first, on Galileo’s arrival in Rome in 1611, he was received in triumph; all the world, clerical and lay, flocked to see him, and, setting up his telescope in the Quirinal Garden belonging to Cardinal Bandim, he exhibited the sunspots and other objects to an admiring throng. However, four years later the ecclesiastical authorities took alarm at the persistence with which Galileo proclaimed the truth of the Copernican doctrine.
They were firmly convinced, with Bacon and others, that the new teaching was radically false and unscientific. But what, more than all, raised alarm was anxiety for the credit of Holy Scripture, the letter of which was then universally believed to be the supreme authority in matters of science, as in all others. When therefore it spoke of the sun staying his course at the prayer of Joshua, or the earth as being ever immovable, it was assumed that the doctrine of Copernicus and Galileo was anti-Scriptural; and therefore heretical. In these circumstances, Galileo, hearing that some had denounced his doctrine as anti-Scriptural, presented himself at Rome in December, 1615, and was courteously received. He was presently interrogated before the Inquisition, which after consultation declared the system he upheld to be scientifically false, and anti-Scriptural or heretical, and that he must renounce it. This he obediently did, promising to teach it no more. Then followed a decree of the Congregation of the Index dated 5 March 1616, prohibiting various heretical works to which were added any advocating the Copernican system.
The pope fully approved the decision, since he had presided at the session of the Inquisition, wherein the matter was discussed and decided. In thus acting, it is undeniable that the ecclesiastical authorities committed a grave and deplorable error, and sanctioned an altogether false principle as to the proper use of Scripture. Galileo rightly urged that the Bible is intended to teach men to go to heaven, not how the heavens go. He left Rome with the evident intention of violating the promise extracted from him, and, while he pursued unmolested his searches in other branches of science, he lost no opportunity of manifesting his contempt for the astronomical system which he had promised to embrace. Nevertheless, when in 1624 he again visited Rome, he met with what is described as a noble and generous reception. The pope now reigning, Urban VIII, had, been his friend and had opposed his condemnation in 1616. He conferred on his visitor a pension, to which as a foreigner in Rome Galileo had no claim, and which, says Brewster, must be regarded as an endowment of Science itself.
But to Galileo’s disappointment Urban would not annul the former judgment of the Inquisition. After his return to Florence, Galileo set himself to compose the work that revived and aggravated all former animosities, namely a dialogue in which a Ptolemist is utterly routed and confounded by two Copernicans. This was published in 1632, and, being plainly inconsistent with his former promise, was taken by the Roman authorities as a direct challenge. He was therefore again cited before the Inquisition, and again failed to display the courage of his opinions, declaring that since his former trial in 1616 he had never held the Copernican theory. Such a declaration, naturally was not taken very seriously, and in spite of it he was condemned as vehemently suspected of heresy to incarceration at the pleasure of the tribunal and to recite the Seven Penitential Psalms once a week for three years. Under the sentence of imprisonment Galileo remained till his death in 1642.
At the end of his trial, as Galileo rose from his knees after renouncing the motion of the earth he said, E pur si muove. (It does move.) This last assertion of this great astronomer serves as fitting epigraph of his discovery-filled life, and of the struggle for truth and science that pervaded the second half of his life. Science Essays.