( Originally Published 1851 )
The 19th of February by some accounts, but according to the best authorities the 15th, is the anniversary of the birth of one of the greatest philosophers of modern times, the celebrated GALILEO GALILEI. He was born at Pisa, in 1564.
His family, which, till the middle of the 14th century, had borne the name of Bonajuti, was ancient and noble, but not wealthy; and his father, Vincenzo Galilei, appears to have been a person of very superior talents and accomplishments. He is the author of several treatises upon music, which show him to have been master both of the practice and theory of that art. Galileo was the eldest of a family of six children, three sons and three daughters. His boyhood, like that of Newton, and of many other distinguished cultivators of mathematical and physical science, evinced the natural bent of his genius by various mechanical contrivances which he produced; and he also showed a strong predilection and decided talent both for music and painting. It was resolved, however, that he should be educated for the medical profession ; and with that view he was, in 1581, entered at the university of his native town. Ile appears to have applied himself, for some time, to the study of medicine. He contrived several little instruments for counting the pulse by the vibrations of a pendulum, which soon came into general use, under the name of Pulsilogies; and it was not till after many years that it was employed as a general measure of time. It was probably after this discovery that Galileo began the study of mathematics. From that instant he seemed to have found his true field. So fascinated was he with the beautiful truths of geometry, that his medical books henceforth remained unopened, or were only spread out over his Euclid to hide it from his father, who was at first so much grieved by his son's absorption in his new study, that he positively prohibited him from any longer indulging in it. After some time, however, seeing that his injunctions were insufficient to overcome the strong bias of nature, he yielded the point, and Galileo was permitted to take his own way. The year 1609 was the most momentous in the career of Galileo as an enlarger of the bounds of natural philosophy
It was in this year that he ma his grand discovery of the telescope having been induced to turn his attention to the effect of a combination of magnifying glasses, by a report which was brought to him, while on a visit at Venice, of a wonderful instrument constructed on some such principle, which had just been sent to Italy from Holland. In point of fact, it appears that a rude species of telescope had been previously fabricated in that country; but Galileo, who had never seen this contrivance, was undoubtedly the true and sole inventor of the instrument in that form in which alone it could be applied to any scientific use.
The interest excited by this discovery transcended all that has ever been inspired by any of the other wonders of science. After having exhibited his new instrument for a few days, Galileo presented it to the Senate of Venice, who immediately elected him to a professorship for life, and made his salary one thousand florins. Ile then constructed another telescope for himself, and with that proceeded to examine the heavens. He had not long directed it to this, the field which has ever since been its principal domain, before he was rewarded with a succession of brilliant discoveries. The four satellites, or attendant moons, of Jupiter, revealed themselves for the first time to the human eye. Other stars unseen before met him in every quarter of the heavens to which he turned. Saturn showed his singular encompassing ring. The moon unveiled her seas and her mountains. The sun himself discovered spots of dark lying in the midst of his brightness. All these wonders were announced to the world by Galileo in the successive numbers of a publication which he entitled the " Nuncius Sidereus, or Intelligence of the Heavens," a newspaper undoubtedly unrivall d for extraordinary tidings by any other that has ever appeared. In 1610 he was induced to resign his professorship at Padua, on the invitation of the Grand Duke of Tuscany to accept of the appointment of his first mathematician and philosopher at Pisa. Soon after his removal thither Galileo appears to have for the first time ventured upon openly teaching the Copernican system of the world, of the truth of which he had been many years before convinced. This bold step drew down upon the great philosopher a cruel and disgraceful persecution which terminated only with his life. An outcry was raised by the ignorant bigotry of the time, on the ground that in maintaining the doctrine of the earth's motion round the sun he was contradicting the language of Scripture, where, it was said, the earth was constantly spoken of as at rest. The day is gone by when it would have been necessary to attempt any formal refutation of this absurd notion, founded as it is upon a total misapprehension of what the object of the Scriptures is, which are intended to teach men morality and religion only, not mathematics or astronomy, and which would not have been even intelligible to those to whom they were first addressed, unless their language in regard to this and various other matters had been accommodated to the then universally prevailing opinions. In Galileo's day, however, the Church of Rome had not learned to admit this very obvious consideration. In 1616 Galileo, having gone to Rome on learning the hostility which was gathering against him, was graciously received by the Pope, but was commanded to abstain in future from teaching the doctrines of Copernicus. For some years the matter was allowed to sleep, till in 1632 the philosopher published his celebrated Dialogue on the two Systems of the World, the Ptolemaic and the Copernican, in which he took but little pains to disguise his thorough conviction of the truth of the latter. The rage of his enemies, who had been so long nearly silent, now burst upon him in a terrific storm. The book was consigned to the Inquisition, before which formidable tribunal the author was forthwith summoned to appear. Ile arrived at Rome on the 14th of February, 1633. We have not space to relate the history of the process. It is doubtful whether or no Galileo was actually put to the torture, but it is certain that on the 21st of June he was found guilty of heresy, and condemned to abjuration and imprisonment. His actual confinement in the dungeons of the Holy Office lasted only a few days; and after some months he was allowed to return to his country seat at Arcetri, near Florence, with a prohibition, however, against quitting that retirement, or even admitting the visits of his friends. Galileo survived this treatment for sever-al years, during which he continued the active per-suit of his philosophical studies, and even sent to the press another important work, his Dialogues on the Laws of Motion. The rigor of his confinement, too, was after some time much relaxed; and although he never again left Arcetri (except once for a few months), he was permitted to enjoy the society of his friends in his own house. But other misfortunes now crowded upon his old age. His health had long been bad, and his fits of illness were now more frequent and painful than ever. In 1639 he was struck with total blindness. A few years before, the tie that hound him most strongly to life had been snapped by the death of his favorite daughter. Weighed down by these accumulated sorrows, on the 8th of January, 1642, the old man breathed his last at the advanced age of seventy-eight. For a full account of Galileo of what he was and what he did the reader ought to peruse his life in the "Library of Useful Knowledge," from which the above rapid sketch has been abstracted. The subject of the philosopher and his times is there treated in ample detail, and illustrated with many disquisitions of the highest interest.