A letter recently discovered by Galileo solves a puzzling historical mystery

Galileo, a famous astronomer, has been hailed for centuries for his courageous position against the Catholic Church. He advocated moving the Earth around the Sun, not the opposite, in direct contradiction to the teachings of the Church at the time. But a long-lost letter was discovered at the Royal Society in London, indicating that Galileo attempted to soften his initial pretensions to avoid the wrath of the church.

In August, Salvatore Ricciardo, a post-doctoral student in history of science at the University of Bergamon in Italy, visited London, looking for handwritten commentaries on Galileo's works in various British libraries. He was flipping through a catalog at the Royal Society when he came across the letter that Galileo wrote to a friend in 1613, setting out his arguments. according to Nature, who first reported the discovery unexpectedly, the letter "provides the strongest evidence that, at the beginning of his fight against religious authorities, Galileo actively engaged in damage control and attempted to release a version lightened of his assertions.

"I thought," I can not believe that I discovered the letter that virtually all Galileo specialists thought was hopelessly lost, "Ricciardo said. Nature. "It seemed even more incredible because the letter was not in an obscure library, but in the library of the Royal Society."

Oh more than the moon

To understand the meaning of this discovery, we must go back to Claudius Ptolemy around 150 AD. J.-C., who was the first to synthesize the work of the Greek astronomers in a theoretical model of the movements of the sun, the moon and the planets. in the observable universe at the time. In his Almagest Ptolemy suggested that the Earth was fixed, placed in the very center of closed spherical space, with nothing beyond it. A set of nested spheres (called "epicycles") surrounded the Earth, each being an orbit for a planet, the Sun, the Moon, or the stars.

"L & # 39; aesthetic [of the Ptolemaic model] agreed well with the dominant Christian theology of that time.

Everyone liked the Ptolemaic model, even if it was an imperfect calendar. It was so clean and symmetrical – positively divine. That's why he was the dominant model for fourteen centuries. The aesthetic accorded well with the dominant Christian theology of that time. All that was underground on Earth was soiled by original sin, while the celestial epicycles above the moon were pure and holy, filled with a divine "music of the spheres". ), to praise their mistresses as "more than the moon" and to reject "the love of sublime sublimates" as inferior and inferior. And this provided a justification for maintaining the social hierarchy. Uphold the order of this "great chain of being", and the result would be boundless chaos.

Everything changed in the middle of the 16th century, when Nicolaus Copernicus published From Revolutionibus, calling for a radical new cosmological model that has placed the Sun at the center of the universe, with other planets orbiting around. His calculations defined the order of the six known planets at the time, and he rightly concluded that it was the rotation of the Earth that explained the changing positions of the stars at night. As for the planets moving in apparent retrograde motion, he concluded that it was because we observe them from a moving Earth.

Frankly, the book did not cause a lot of unrest outside the rarefied astronomical circles, perhaps because it was a huge book filled with boring mathematics. He did not list the forbidden books of the church until 1616. It was at that time that he was withdrawn from circulation while waiting. " correction "to reflect that his bold affirmations were" just a theory "creationism.

Then Galileo came with his practical telescope (a recent invention) and his observations clearly supported the Copernican world view. The church began to take note, because Galileo openly married the Copernican system, in his papers and his personal correspondence. In 1632, things went wrong when he published the "Dialogue Concerning the Two Great World Systems". It was not just the science that made the eyebrows stand out. He also had the audacity to question the key biblical passages generally presented in support of Ptolemaic cosmology, insisting that the Bible is meant to teach people how to go to heaven and not on a scientific treatise on how the heavens move.

The Catholic Church had had enough and Galileo found himself facing the Inquisition, forced to kneel to formally renounce his "belief" in the Copernican worldview. He was convicted of "vehement heresy" and spent his last nine years under house arrest. He was officially pardoned by the Vatican only in 1992.

Hiding at the sight

It's the story as it is traditionally told. So what has changed? Galileo's letter to a mathematician from the University of Pisa, Benedetto Castelli, is in question. This is the first known case where he pleaded for the Copernican model and that scientific observations should supplant the teaching of the church in astronomy. This letter was copied and widely distributed (a common practice in the 1600s) and a copy was found in the hands of a Dominican friar, Niccolo Lorini. Annoyed by heretical implications, Lorini forwarded the letter to the Inquisition in Rome on February 7, 1615. It is currently kept in the Vatican's secret archives.

Here is where it gets complicated. Galileo asked Castelli to return his original letter of 1613. On February 16, 1615, he wrote to a Roman friend, Piero Dini, claiming that Lorini ("wickedness and ignorance") had tampered with the copy of the letter sent to the 39 Inquisition for Galileo to be guilty of heresy. He joined a different version of the Castelli letter, with a significantly less inflammatory language, claiming that it was the correct version.

Historians did not know which of the two versions was the right one, the original having been considered lost – until Ricciardo discovered it hidden under the eyes of the Royal Society. According to Ricciardo, the catalog indicated the date of October 21, 1613, but the current letter is dated December 21, 1613. It is perhaps for this reason that so many previous scholars have ignored it. This is also an unusual item for the Royal Society in its archives. The Company is currently trying to trace its provenance to determine how it ended up there.

The letter provides a solid proof that Galileo was the one who was here and deliberately altered the version he had asked Dini to convey to the Inquisition, in the hope of appeasing the anger of the church. By Nature:

Under its stripes and modifications, the signed copy discovered by Ricciardo shows the original formulation of Galileo – and it is identical to that of the Lorini copy. The changes are revealing. In one case, Galileo described some Bible proposals as "false if we rely on the literal meaning of the words". He went through the word "false" and replaced it with "different from the truth". In another section, he changed his reference to the scriptures "hiding" his most basic dogma, to the weaker "veil".

Ricciardo and his colleagues – Franco Giudice of the University of Bergamo and the historian of science Michele Camerota of the University of Cagliari – conducted their own analysis of writing. They compared individual words in the newly discovered letter with similar words in Galileo's other writings around the same period. They concluded that the writing was that of Galileo.

Should we conclude that Galileo was not the scientific hero we had long thought to be? Surely not. The changes are minor, mainly with respect to his statements on the Bible, not his scientific analysis. It is difficult for us to conceive how dangerous the 16th century was for scientists and scholars who dared to cross the Catholic Church. Galileo was fortunate not to have been burned at the stake for his claims; Thousands of less fortunate people around the world have been executed for heresy during the centuries of the Inquisition's existence. Who could blame him for the past nine years of calm and relative contemplation? This just shows the complicated man behind the heroic stereotype – a man with sufficient diplomatic talent to soften his words without diluting his science.

[h/t Nature]