Today Galileo is a famous and romantic name. We have all been taught the story of his heroic fight in the name of science against the intractable ignorance of the tyrannical Catholic church. The reality is not so starkly drawn, but no less interesting for that; Galileo's own arrogance created many enemies, and Rome's anxiety over its authority in the schismatic era of the Protestant reformation made their collision inevitable.

Galileo was a professor of mathematics, first at the University of Pisa, where he had been born, and then at Padua, perhaps establishing a reputation for his willingness to offend Aristotelian philosophers perhaps, with the publication of De Motu (On Motion), but for little more. But while continuing to work as a mathematician, Galileo's interest in philosophy (i.e., physics) and then astronomy grew. With the publication of Siderius Nuncius, or The Starry Messenger, in 1610--in which he recorded the sights he had seen with the newly invented telescope, including the moons of Jupiter, and the mountains of our own moon-Galileo was instantly famous across Europe. He was also in the midst of controversy, for few believed him until his findings could be verified by others with what was still a very rare instrument (Galileo had made his own) and even then there were disputes as to what those finding really were. This controversy was no impediment to his ambitions, and his cultivation of the patronage of Cosimo de Medici, Duke of Florence-to whom he had dedicated his book, and whose name he gave to the Jovian moons-led to his being named "Chief Mathematician of the University of Pisa and Philosopher to the Grand Duke." Mathematicians and astronomers were not equivalent in the hierarchy of arts to philosophy, and in his new position Galileo's wars with the Aristotelian philosophers escalated, for physics was becoming his principle interest.

In 1615 he went to Rome to argue on behalf of the merits of the Copernican theory, but the political atmosphere was such that Copernicus' De Revolutionibus was placed on the Index of Prohibited Books in 1616, and his theory declared "foolish and absurd philosophically and formally heretical inasmuch as it expressly contradicts the doctrines of the holy scripture." There is evidence that Galileo was warned against promoting the Copernican theory at this time. A Dialogue Concerning the Two Chief World Systems first made it past the censors by purporting to be neutral on the astronomical debate. Its failure to do so was but one of the objections raised after publication.

It had taken the Catholic Church seventy-three years to deem it neccessary to ban De Revolutionibus, but when Galileo published A Dialogue Concerning the Two Chief World Systems in 1632, it reacted within in five months, and in 1633 his famous trial and recantation took place.