Galileo Galilei's "Letter to Benedetto Castelli" (1613) was his first statement on the authority of scripture and the Catholic Church in matters of scientific enquiry.
[2]: 27 Galileo usually avoided referring to scripture in his arguments about the universe, while the Aristotelian scholars who opposed Copernicus cited the Bible in support of their views – for example Lodovico delle Colombe in his 1611 work Contra il Moto della Terra (Against the Motion of the Earth) explicitly challenged anyone defending Copernicus to answer the charge that he was going against what the Bible taught.
After the dinner, Castelli had been called back by the Dowager Duchess Christina of Tuscany to answer points she raised from scriptural arguments against the motion of the Earth.
[6] His letter argues a position on scriptural authority which is very similar in substance, if not in tone, to that set out by the Catholic Church itself centuries later, in Leo XIII's 1893 encyclical, Providentissimus Deus.
Emphasising that the Bible makes use of figurative language and is not meant to teach science, this argues: "...here is the rule also laid down by St. Augustine, for the theologian: "Whatever they [i.e. scientists] can really demonstrate to be true of physical nature, we [i.e. theologians] must show to be capable of reconciliation with our Scriptures; and whatever they assert in their treatises which is contrary to these Scriptures of ours, that is to Catholic faith, we must either prove it as well as we can to be entirely false, or at all events we must, without the smallest hesitation, believe it to be so.
"[8] In late 1614 or early 1615, Niccolò Lorini obtained a copy of Galileo's letter, some parts of which he and his fellow Dominicans at the convent of San Marco in Florence adjudged to be "suspect or rash".
[10][11] He therefore forwarded it to Cardinal Paolo Emilio Sfondrati at the Congregation of the Index, together with a covering letter dated 7 February 1615, calling for the matter to be investigated.
[1]: 71 Lorini's version also included the phrase 'Scripture does not refrain from perverting its most important dogmas...' whereas Galileo's original had said 'Scripture accommodates itself to the capacity of uncouth and uneducated people'.
[1]: 197 For whatever reason, the Holy Office wished to make certain that it had an accurate version before proceeding with its investigation, so Cardinal Garzia Mellini, secretary of the Inquisition, wrote to the archbishop of Pisa, where Castelli taught at the university, and asked him to provide the original letter.
He made a copy of it and sent this version to his friend Archbishop Piero Dini in Rome, protesting at the “wickedness and ignorance” of his enemies, and expressing concern that the Inquisition “may be in part deceived by this fraud which is going around under the cloak of zeal and charity”.
That adviser's report, undated, concluded that there were three places where Galileo had used language which was offensive, but 'although this document sometimes uses words improperly, it does not deviate from the narrow path of Catholic expression.