Galileo Galilei (1564-1642) has rightly been considered to be one of the greatest scientists in history. Best known for his revolutionary seventeenth-century theories of celestial motion, holding the view that planets were not fixed in space in which all other planetary bodies revolved around it  but, in fact, planets revolved around the sun (a theory similarly advocated by Galileo’s predecessor Nicolaus Copernicus). This theory would contradict the held doctrinal belief of the Catholic Church that the Earth was fixed in the heavens. Galileo would find relative safety in the patronage of the era’s most influential family, but his immunity would quickly disintegrate after publishing his observations in Dialogo sopra I due massimi sistemi del mondo, tolemaico e copernicano (click here to read Dialogue Concerning the Two Chief Systems of the World – Ptolemaic and Copernican) in 1632. It would not be long before Pope Urban VIII (Maffeo Barberini) would authorize a special commission to examine the book and, subsequently, summon Galileo to Rome in October 1632 to defend his heretical actions before the Inquisition. It is important to note that Galileo had to defend his Copernican view once before in 1616, in which an inquisition ordered him to not “hold, teach, nor defend” Copernican theory. His summons and arrival in Rome in February 1633 and subsequent events would be a very different outcome for Galileo.

In The Trial of Galileo Doug Linder notes the climate that led to Galileo’s summons and trial: “Galileo’s world of science and humanism collides with the world of Scholasticism and absolutism that held power in the Catholic Church. The result is a tragedy that marks both the end of Galileo’s liberty and the end of the Italian Renaissance.”

Although Galileo’s health had been particularly fragile in the buildup to his summons and trial, his request to defend his theory in Florence rather than in Rome was hastily rejected. The Inquisition ignored the advice of three physicians who declared Galileo unfit to travel, leaving him with no other choice than to travel to Rome. The almost 300km journey to Rome took Galileo twenty-three days at which time he took up residence under sanction to halt all social contacts at the Florentine embassy. By April 1633, Galileo was informed that he would stand trial before a commission of cardinals – knowing that his fate had most certainly been previously decided.

On April 12, 1633 Galileo officially surrendered to the Holy Office in Rome where he underwent his first of many depositions (click here to read Galileo’s Depositions). Having surrendered, the Inquisition informed Galileo that he would be imprisoned at the inquisition building in Rome. The Inquisition would base most of their criticism of Galileo on his violation of the sanctions placed on him back in 1616 for promoting Copernican views. The cardinals prepared a seven-page evaluation of the Dialogue. The report concluded that Galileo taught, defended, and revealed that he held Copernican theory and gave the Copernican model “a physical reality.” Upon intense internal debate among the commission of cardinals, it took weeks to conclude what was to be done with Galileo. Cardinal Francesco Barberini – who held sympathy for Galileo – persuaded the cardinals to convince Galileo to admit his error in return for a more lenient sentence.

A letter only discovered in 1833 details Francesco Barberini’s discussions with Galileo. “I entered into discourse with Galileo yesterday afternoon, and after many arguments and rejoinders had passed between us, by God’s grace, I attained my object, for I brought him to a full sense of his error, so that he clearly recognized that he had erred and had gone too far in his book.”

The trial itself was not conventional in the sense that we envision a trial to occur. Galileo was imprisoned for the duration of the trial and only questioned in between long debates by the cardinals. As the trial approached a conclusion, a number of cardinals – and indeed the Pope – pushed for a harsh verdict that would send a strong message to those whose heretical writings would seek to challenge the Church’s supremacy and the Ptolemaic theory that underpinned the belief that the Earth stood at the centre of the cosmos.

On June 22, 1633 the Inquisition delivered its Papal Condemnation (Sentence) of Galileo (click here to read the entire Papal Condemnation here). An excerpt from the sentence reads as follows:

“We say, pronounce, sentence, and declare that you, the said Galileo, by reason of the matters adduced in trial, and by you confessed as above, have rendered yourself in the judgment of this Holy Office vehemently suspected of heresy, namely, of having believed and held the doctrine—which is false and contrary to the sacred and divine Scriptures—that the Sun is the center of the world and does not move from east to west and that the Earth moves and is not the center of the world; and that an opinion may be held and defended as probably after it has been declared and defined to be contrary to the Holy Scripture; and that consequently you have incurred all the censures and penalties imposed and promulgated in the sacred canons and other constitutions, general and particular, against such delinquents. From which we are content that you be absolved, provided that, first, with a sincere heart and unfeigned faith, you abjure, curse, and detest before use the aforesaid errors and heresies and every other error and heresy contrary to the Catholic and Apostolic Roman Church in the form to be prescribed by us for you.

And in order that this your grave and pernicious error and transgression may not remain altogether unpunished and that you may be more cautious in the future and an example to others that they may abstain from similar delinquencies, we ordain that the book of the “Dialogues of Galileo Galilei” be prohibited by public edict.

We condemn you to the formal prison of this Holy office during our pleasure, and by way of salutary penance we enjoin that for three years to come you repeat once a week at the seven penitential Psalms. Reserving to ourselves liberty to moderate, commute or take off, in whole or in part, the aforesaid penalties and penance.”

Found guilty, Galileo was condemned to life imprisonment. His Dialogue was also prohibited. Galileo’s sentence was commuted to house arrest (most likely out of sympathy for the sick and elderly Galileo). Two days after the verdict Galileo was released to the custody of the Florentine ambassador. Transferred to the Archbishop Piccolomini in Sienna Galileo found a kind and hospitable friend in Piccolomini. That friendship afforded Galileo the energy to complete his final book: Discourses and Mathematical Demonstrations Relating to Two New Sciences. Receiving permission from the Roman Inquisition to return to Florence, Galileo moved into his home in Arcetri where his health would further degrade rendering him blind. In January 1642 the eminent Galileo Galilei died.

The tragedy – indeed travesty of justice – that was the summons, trial, and sentence of Galileo was perpetuated by the Catholic Church until in 1992 it finally admitted to its wrongdoing, 350 years after Galileo’s death. Even out of fear of retribution from the Church, Galileo’s family did not inter Galileo’s body in his family tomb in the Basilica of Santa Croce (Florence) until 1737. Although the Church’s apology in 1992 stopped short of admitting that it was wrong to convict Galileo of heresy, it did acknowledge his profound contribution to science.

Pope John Paul II delivered the following words in November 1992:

“Thanks to his intuition as a brilliant physicist and by relying on different arguments, Galileo, who practically invented the experimental method, understood why only the sun could function as the centre of the world, as it was then known, that is to say, as a planetary system. The error of the theologians of the time, when they maintained the centrality of the Earth, was to think that our understanding of the physical world’s structure was, in some way, imposed by the literal sense of Sacred Scripture….” — Pope John Paul II, L’Osservatore Romano N. 44 (1264) – November 4, 1992.

History always provides us with valuable lessons. Galileo Galilei was a testament to the brilliance of the human mind suppressed by the power of an institution bent on maintaining its supremacy over knowledge and truth. Galileo would be not only a precursor to untold scientific advancement but indeed the Enlightenment itself. The eminent Galileo must be remembered for his achievements in astrology, engineering, physics, and mathematics that support a legacy that changed the course of human history. Galileo is now rightly held as a bulwark of the power of truth, rationality, and greatness. Knowledge will also be on trial so to speak, and it is our duty to ensure that whatever direction human history takes we may stand for the unrestrained full capacity of individual and collective human achievement.

Cover image: “Galileo Before the Holy Office” – Joseph-Nicolas Robert-Fleury, 1847