Astronomer Galileo Galilei’s theories of the universe placed him in trouble with the Catholic Church. He argued that Earth and the other planets orbit around the sun, which is in direct contradiction to the teachings of the church during his time.

A newly discovered letter of the father of observational astronomy now revealed what he did to avoid the wrath of the powerful church, and this involved some old-fashioned trickery.

Salvatore Ricciardo, a historian from the University of Bergamo in Italy, discovered the seven-page letter while flipping through a catalog at the Royal Society in London. As Nature details, The letter was addressed to Galileo’s friend, mathematician Benedetto Castelli, and is dated Dec. 21, 1613.

Within, Galileo wrote that the heliocentric model of the solar system — which argues that the planets rotate around the sun — did not inherently contradict the Bible. Galileo reasoned that the scant references to astronomical events in the scriptures should not be taken literally because the scribes who wrote them simplified the descriptions so that common people could understand them.

In 1615, the Inquisition got ahold of the letter and forwarded the missive to Dominican friar Niccolò Lorini. Concerned with the possible consequences, Galileo made a move to appease the church.

Evidence showed that Galileo wrote a different and more delicately phrased version of the original letter. He then asked a friendly cleric in Rome — Piero Dini — to pass this along to the Vatican, with the claim that his enemies in the Church doctored the original letter to make him look bad.

Featured image credit: Hulton Archive Getty Images

“The changes are telling. In one case, Galileo referred to certain propositions in the Bible as “false if one goes by the literal meaning of the words”. He crossed through the word “false”, and replaced it with “look different from the truth”,” Alison Abbott of Nature wrote.

Abbott, who first reported the discovery, said that the letter provided the strongest evidence to date that at the start of his battle with religious authorities of his time, Galileo engaged in damage control by spreading a toned-down version of his claims.

Despite Galileo’s efforts, however, the Inquisition ordered him to abandon his defense of the heliocentric model in 1616. He was later put on trial because of his scientific theories. In 1633, Galileo was convicted of a “strong suspicion of heresy”. He lived out his days on a rigidly enforced house arrest, and died nine years later.

Ricciardo and colleagues are now trying to determine when the letter arrived at the Royal Society Library — and how long it has been in there.