New Advent Catholic Encyclopedia: Galileo Galilei
Generally called GALILEO. Born at Pisa, 15 February, 1564; died 8 January, 1642.
Only in 1734 did the Church finally give permission for a mausoleum to be built for Galileo's remains (XIX, 399), which were moved to the completed structure in 1736. The inscription read Galileo Galilei, Florentine Patrician, very great Innovator of Astronomy, of Geometry and of Philosophy. However, the attendant allegories are Astronomy and Geometry. The Church would not allow Philosophy (ie: Science) to be included, as that is what he was brought to trial over.
His father, Vincenzo Galilei, belonged to a noble family of straitened fortune, and had gained some distinction as a musician and mathematician. The boy at an early age manifested his aptitude for mathematical and mechanical pursuits, but his parents, wishing to turn him aside from studies which 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 in the very first rank of natural philosophers.
It is the great merit of Galileo that, happily combining experiment with calculation, he opposed the prevailing system according to which, instead of going directly to nature for investigation of her laws and processes, it was held that these were best learned by authority, especially by that of Aristotle, who was supposed to have spoken the last word upon all such matters, and upon whom many erroneous conclusions had been fathered in the course of time. Against such a superstition Galileo resolutely and vehemently set himself, with the result that he not only soon discredited many beliefs which had hitherto been accepted as indisputable, but aroused a storm of opposition and indignation amongst those whose opinions he discredited; the more so, as he 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. As Sir David Brewster (Martyrs of Science) says, "The boldness, may we not say the recklessness, with which Galileo insisted on making proselytes of his enemies, served but to alienate them from the truth."
Although in the popular mind Galileo is remembered chiefly as an astronomer, it was not in this character that he made really substantial contributions to human knowledge -- as is testified by such authorities as Lagrange, Arago, and Delambre -- but rather in the field of mechanics, and especially of dynamics, which science may be said to owe its existence to him. Before he was twenty, observation of the oscillations of a swinging lamp in the cathedral of Pisa led him to the discovery of the isochronism of the pendulum, which theory he utilized fifty years later in the construction of an astronomical clock. In 1588, a treatise on the centre of gravity in solids obtained for him the title of the Archimedes of his time, and secured him a lecture-ship in the University of Pisa. During the years immediately following, taking advantage of the celebrated leaning tower, he laid the foundation experimentally of the theory of falling bodies and demonstrated the falsity of the peripatetic maxim, hitherto accepted without question, that their rate of descent is proportional to their weight. This at once raised a storm on the part of the Aristoteleans, who would not accept even facts in contradiction of their master's dicta. Galileo, in consequence of this and other troubles, found it prudent to quit Pisa and betake himself to Florence, the original home of his family. By the influence of friends with the Venetian Senate he was nominated in 1592 to the chair of mathematics in the University of Padua, which he occupied for eighteen years, with ever-increasing renown. He afterwards betook himself to Florence, being appointed philosopher and mathematician extraordinary to the Grand Duke of Tuscany. During the whole of this period, and to the close of his life, his investigation of Nature, in all her fields, was unwearied. Following up his experiments at Pisa with others upon inclined planes, Galileo established the laws of falling bodies as they are still formulated. He likewise demonstrated the laws of projectiles, and largely anticipated the laws of motion as finally established by Newton. He studied the properties of the cycloid and attempted the problem of its quadrature; while in the "infinitesimals", which he was one of the first to introduce into geometrical demonstrations, was contained the germ of the calculus. In statics, he gave the first direct and entirely satisfactory demonstration of the laws of equilibrium and the principle of virtual velocities. In hydrostatics, he set forth the true principle of flotation.