An epic, earth-moving battle

Galileo is one of only a handful of people in history who are referred to by their first name, a trait he shares with Napoleon, Jesus, Dante and Michelangelo. Among scientists, he is habitually ranked with Newton, Einstein and Darwin. But among the illuminati with whom he is normally bracketed, his was the most complex life, in which his incomparable distinction in research became entangled with his epic struggle with the theologians that culminated in the famous trial in 1633. Galileo is unique among great scientists because he alone had to withstand the fury of a world power intent not only on suppressing his theories, but also on harshly punishing him as an example to those who were promoting his works.

The central theme of Michael White's lively biography is a full examination of Galileo and the Church. The coverage of Galileo's achievements in science is perhaps too slight to satisfy professional historians of science, although White's coverage of the development of the military compass by Galileo shows the latter to be a capable entrepreneur with an eye on the main chance. Galileo's telescopic discoveries of 1610, and the manner in which he chose to publicise them, set the scene for the first clash with the theologians.

The Copernican vision of a sun-centred universe, published in 1543, took decades to gain a foothold. When Galileo proposed that his telescope confirmed the Copernican hypothesis, almost 70 years after the death of its architect, no major natural philosopher other than Kepler had come out in favour of the Polish canon's revolutionary ideas. The common assertion that the Roman theologians in the 1610s feared Copernicanism is a misunderstanding. White corrects this by setting out with commendable clarity the panic in the Vatican when Galileo started to use the new scientific method to question the authority of the Bible and the doctors of the Church. In the Vatican, the battle was all about the interpretation of Scripture, now challenged by Galileo's new philosophy in which the Earth moved.

As Galileo put it starkly, in an open letter of 1615, the central issue for him was the confrontation between "certainties in physics" and "human writings that are supported only by bare assertions". But this would not do in Rome. He was summoned to a trial in 1616, orchestrated by Pope Paul V, that led to his acquiescence in which he promised that he would not teach Copernicanism as anything more than a hypothesis.

The Galileo affair took off when Pope Urban VIII launched the trial before the Inquisition in April 1633. Galileo was by then an arrogant and supremely confident man with many enemies in the Vatican. In March 1632, his latest book, Dialogue Concerning the Two Chief World Systems , arrived in Rome, where it immediately created a sensation despite the fact that the papal censors had authorised its publication. Galileo's Jesuit enemies regarded the book as a disgraceful attack on Urban VIII, whose ideologies are voiced in the dialogue by a simpleton. Furthermore, Galileo had broken the injunction of 1616 not to teach Copernicanism. After a hearing, the Inquisition sentenced him to life imprisonment, which was commuted to house arrest.

White's account of the trial has a twist: a conspiracy theory. He argues that Galileo had stumbled on ideas about the nature of matter that were so dangerous that they threatened the foundations of Catholicism.

Apart from Copernicanism, Galileo had also been promoting an atomic theory of matter. An intriguing document dating from 1631, denouncing atomism as being contrary to the doctrine of the Eucharist, surfaced in the Vatican archives 25 years ago. Pietro Redondi, the scholar who uncovered that document, used it in a reinterpretation of the Galileo affair, claiming that Urban VIII, a former friend of Galileo, manipulated the proceedings so that Galileo would face charges only in connection with Copernicanism, while atomism charges would not be raised.

Although initial work for the trial may have been influenced by this document, the well-known facts of the Galileo affair remain unchallenged. What was at stake was his failure to obey a formal warning not to promote the claim that the Earth moved at a time when papal authority was at its most vulnerable.

Simon Mitton is a fellow of St Edmund's College, Cambridge.