In the 1633 trial of Galileo Galilei, two worlds come into cosmic conflict. Galileo's world ofscience and humanism collides with the world of Scholasticism and absolutism that held power inthe Catholic Church. The result is a tragedy that marks both the end of Galileo's liberty and theend of the Italian Renaissance.
Galileo Galilei was born in 1564--the same year that Shakespeare was born and Michelangelodied. From an early age, Galileo showed his scientific skills. At age nineteen, he discovered theisochronism of the pendulum. By age twenty-two, he had invented the hydrostatic balance. Byage twenty-five, Galileo assumed his first lectureship, at the University of Pisa. Within a fewmore years, Galileo earned a reputation throughout Europe as a scientist and superb lecturer.Eventually, he would be recognized as the father of experimental physics. Galileo's mottomight have been "follow knowledge wherever it leads us."
At the University of Padua, where Galileo accepted a position after three years in Pisa, he beganto develop a strong interest in Copernican theory. In 1543, Nicolaus Copernicus publishedRevolutions of the Celestial Orbs, a treatise that put forth his revolutionary idea that the Sunwas at the center of the universe and that the Earth--rotating on an axis--orbited around thesun once a year. Copernicus' theory was a challenge to the accepted notion contained in thenatural philosophy of Aristotle, the astronomy of Ptolemy and the teachings of the Church thatthe sun and all the stars revolved around a stationary Earth. In the half-century since itspublication, however, Copernicus' theory met mostly with skepticism. Skeptics countered withthe "common sense" notion that the earth they stood on appeared not to move at all--muchless at the speed required to fully rotate every twenty-four hours while spinning around thesun.
Sometime in the mid-1590s, Galileo concluded that Copernicus got it right. He admitted asmuch in a 1597 letter to Johannes Kepler, a German mathematician who had written aboutplanetary systems: "Like you, I accepted the Copernican position several years ago anddiscovered from thence the cause of many natural effects which are doubtless inexplicable bythe current theories." Galileo, however, continued to keep his thoughts to a few trustedfriends, as he explained to Kepler: "I have not dared until now to bring my reasons andrefutations into the open, being warned by the fortunes of Copernicus himself, our master, whoprocured for himself immortal fame among a few but stepped down among the great crowd."
Galileo's discovery of the telescope in 1609 enabled him to confirm his beliefs in the Copernicansystem and emboldened him to make public arguments in its favor. Through a telescope set inhis garden behind his house, Galileo saw the Milky Way, the valleys and mountains of the moon,and--especially relevant to his thinking about the Copernican system--four moons orbitingaround Jupiter like a miniature planetary system. Galileo, a good Catholic, offered "infinitethanks to God for being so kind as to make me alone the first observer of marvels kept hiddenin obscurity for all previous centuries." Galileo began talking about his observations at dinnerparties and in public debates in Florence, where he has taken up a new post.
Galileo expected the telescope to quickly make believers in the Copernican system out of alleducated persons, but he was disappointed. He expressed his discouragement in a 1610letter to Kepler: "My dear Kepler, what would you say of the learned here, who, replete with thepertinacity of the asp, have steadfastly refused to cast a glance through the telescope? Whatshall we make of this? Shall we laugh, or shall we cry?" It became clear that the Copernicantheory had its enemies.
Galileo's first instinct was turn to acquiring more knowledge for those few open minds he wasable to reach--disciples such as monk Benedetto Castelli. Galileo wrote to Castelli: "In order toconvince those obdurate men, who are out for the vain approval of the stupid vulgar, itwould not me enough even if the stars came down on earth to bring witness aboutthemselves. Let us be concerned only with gaining knowledge for ourselves, and let us findtherein our consolation."
Soon, however, Galileo--flamboyant by nature--decided that Copernicus was worth a fight. Hedecided to address his arguments to the enlightened public at large, rather than thehidebound academics. He saw more hope for gaining support among businessmen, gentlemen,princes, and Jesuit astronomers than among the vested apologists of universities. He seemedcompelled to act as a consultant in natural philosophy to all who would listen. He wrote intracts, pamphlets, letters, and dialogues--not in the turgid, polysyllabic manner of a universitypedant, but simply and directly.