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405-year-old letter suggests Galileo toned down his beliefs

The Royal Society Document sent to mathematician Benedetto Castelli by GalileoThe Royal Society

A letter found at the Royal Society in London, where it had been held for at least 250 years, suggests that Italian astronomer Galileo Galilei (1564–1642) softened his stance against the ecclesiastical doctrine that the Sun orbited Earth to avoid arrest by the Roman Inquisition. The letter had been lost for centuries due to a cataloging error. It was only recently discovered by researchers from the University of Bérgamo, Italy. In the letter, written on December 21, 1613, to his friend Benedetto Castelli, a mathematician at the University of Pisa, Galileo argued that biblical references to astronomical events should not be taken literally because they would have been simplified so as to be understood by laypeople. He also stated that the heliocentric model proposed by Nicolaus Copernicus in 1543, in which Earth orbits the Sun, was not incompatible with the Bible. Two versions of the letter were found. The first, passed on to the Inquisition by Friar Niccolò Lorini on February 7, 1615, was more forceful and was used as evidence in the astronomer’s trial in 1633. It was already known that Castelli had given a copy of the letter to Lorini and that on February 16, 1615, Galileo had written to Piero Dini, a clergyman in Rome, suggesting that the version presented to the Vatican by Lorini had been altered. Galileo included his version of the letter, which he said was the original, and asked that it be delivered to the authorities. Since this version was lost, it had previously been impossible to know whether the clerics had altered Galileo’s words or whether the astronomer had written the stronger version and then softened his position. The newly discovered letter contains erasures and amendments, all in Galileo’s handwriting and made after Castelli returned it to him, suggesting that the astronomer rewrote the letter he sent to the authorities to moderate his words.