In a letter to Duchess Cristina de Lorraine, Galileo wrote: “The Bible was not written to teach us astronomy (…) nor to show us what the sky is like, but how to go to it.” It was part of a long and iconic letter with which the Florentine scientist tried to contain the accusations that had begun to be poured out on him from ecclesiastical circles. The year was 1613, Galileo was almost fifty years old and, with that letter, he naively thought that the controversy with the Church would be close to ending. He could not imagine that, in reality, everything had just begun.
The trial of Galileo Galilei by the Inquisition —the court that condemned crimes related to the Catholic faith— is one of the great historical episodes of the Modern Age. Since then, it has sparked heated debates and has been used very often as proof of the alleged intransigence and religious closure in the face of the unstoppable scientific advances that occurred as a result of the appearance of modern science, which has Galileo himself, precisely, as a kind of father.
Why did the “Galileo Case” occur? What did this long legal process consist of and what consequences did it have for the life of the scientist and for science in general? Let’s travel to that Europe of the 17th century to find out.
An eye to look at the universe
Thousands of years before us , the Mesopotamians and the Egyptians already looked at the sky to contemplate the stars . From them we learned to look up and scan the sky looking for possible answers to human questions. Thus, looking at the sky, the first gods were born, the months of the year or the days of the week. But when Galileo was able to look at the sky with his invention, the telescope – one of the most important in history – he did not see sky gods, but mountains on the Moon, sunspots or satellites that surprisingly orbited around Jupiter.
The telescope had changed science completely. Galileo had not actually invented it—we owe the honor to a lens maker, Hans Lippershey—but rather perfected it and used it to start investigating the universe. And it is that, suddenly, the firmament seemed to have no secrets for the Florentine: he observed the Moon in detail, discovered the phases of Venus, the nature of the Milky Way and —of capital importance, as we will see later— the four satellites of Jupiter : Callisto, Europa, Ganymede and Io. Those four satellites revolved around the great planet, something very important that, according to Galileo, showed that the Earth was nothing more than an ordinary planet and that not all the celestial bodies revolved around it.
Thanks to the conscientious observation of the sky, Galileo was able to demonstrate for the first time the heliocentric theory enunciated by Copernicus, which at that time was an astronomical model that affirmed that the Earth and the planets move around the Sun , which is at the center of the universe. The proposition of the Polish clergyman, a milestone in the history of science, was known as the “Copernican revolution” . With this, he dealt a heavy blow to the Aristotelian geocentric theory and, in the same way, corrected certain errors in the Copernican model by affirming —as Copernicus did— that all the heavenly bodies revolved around the Sun.
These discoveries, which Galileo spoke of in his book Sidereus nuncius , brought him great fame and he was received in Rome in 1611 with the honors of a great scientist. However, criticism of his theories began to be noted, and this is when Cardinal Roberto Bellarmine comes into play, an inquisitor who had already favored a decade before the scientist Giordano Bruno was burned alive at the stake. It was him whom the Holy See ordered to investigate whether there could be an accusation of heresy behind Galileo’s work. And as the good old Don Quixote would say: “We have run into the Church, friend Sancho.”
With the Church we have run into
Galileo’s discoveries earned him both fame and opposition from some of his colleagues. Among them, that of the Jesuits of the College of Rome, who refused to take a look through the telescope when Galileo himself visited the city. Those criticisms were at first those of small voices that did not prevent the scientist from continuing his research. However, he was aware of the criticism that was poured on him, so, through a series of letters, he began to defend his discoveries in the only way he knew how: ardently and passionately. In this way, he wrote to his disciple Benedetto Castelli ridiculing those who questioned heliocentrism. The controversy grew larger and larger, forcing Galileo to write to his benefactor Cristina de Lorraine, defending the Copernican arguments. But his explanation came too late: the Holy Office had already begun to investigate the case. There was no going back.
On February 16, 1616, a sick and disgruntled Galileo was summoned before the feared Cardinal Bellarmine, although he ultimately failed to appear before him. After consideration by the court, it was ruled that Galileo “must entirely abandon the view that the Sun stands still in the center of space and the Earth moves around it, and henceforth not hold, teach or defend in any way this doctrine, either orally or in writing.
The censorship of the Copernican theories had begun, which Galileo not only did not accept, but fought for the rest of his life until his dramatic abjuration, publicly criticizing his opponents. But, without a doubt, the important question is: what interest did the Church have in attacking the heliocentric theory so hard?
The reasons for the attack of the Church
They were basically three. In the first place, from the point of view of the Church, Galileo attacked the principles of Aristotelian physics , based on deductive reasoning from arguments of authority, such as that of Aristotle himself or of the Holy Scriptures. Contrary to all this, Galileo defended a new method of doing science: that of inductive reasoning, based on the observation of reality, typical of the scientific method of which Galileo laid the foundations to this day.
Secondly, the heliocentric theory generated a conflict of a religious nature , since it seemed to contradict some passages in the Bible in which it is stated that the Earth is stationary and the Sun moves around it. And we must also take into account a third factor of a political nature : in 1618 the Thirty Years’ War had begun, precisely for religious reasons. From then on, the Church’s efforts to root out any doctrine that seemed to move away from the faith were swift. And Galileo entered the bosom of the dispute.
The censorship of the Inquisition kept Galileo away from scientific experimentation for a few years, although he would soon resume his studies thanks to the improvement of the telescope and new discoveries that would suddenly help him to reaffirm his heliocentric theory, which was still at the center of the debate. And it is that, fifteen years after his first conviction, Galileo found a new hypothesis related to something as common as the movement of the tides.
Why are the tides produced? the scientist wondered. The answer could not be other than that movement of the Earth that the scientist had spent his whole life trying to prove, and that contradicted Jesuit astronomers, who postulated that the tides were produced by the attraction of the Moon. Although finally the Galilean thesis would be shown to be wrong, that fueled the controversy again and, also, the indomitable character of the Pisan, who in 1632 —in the twilight of his life— published his masterpiece: Dialogues on the two maximum systems of the world , Ptolemaic and Copernican . How did this work get past the censorship to which heliocentric theories had been subjected years ago? Perhaps thanks to the friendship that the new pope, Urban VIII, professed with Galileo. Even so, that friendship did not free him from a new call: in October 1632, the Holy Office of the Inquisition once again required him in Rome.
trial of a scientist
Galileo was weighed down by his 68 years , most of which he had spent looking at the sky and contemplating the universe. Sick and almost blind, it took him a few months to respond to the request of the Inquisition. He did so when in December 1632 he was compelled to report immediately with the threat of using force against him.
The process began in April 1933 in the Basilica of Santa Maria sopra Minerva and lasted no less than 70 days . We only have a few minutes of the trial. One of them, the one related to the first days, recounts the long interrogation to which the accused was subjected, in which he admitted the charges against him —the suspicion of serious heresy— and submitted to the authority of the Church .
However, this did not deprive Galileo of defending, days later, the great argument of his scientific work, albeit seeking a balance between science and faith. To do this, he questioned the literalness of the sacred texts and argued that the scientific method was actually a gift from God with which to observe nature and interpret the Scriptures.
But that balance between science and faith that Galileo tried to show in his arguments did not serve his defense. The radicalization of the process led its critics to go from defending that the heliocentric model could be valid, but not absolute truth, to end up considering that Galileo’s texts were nothing more than heresy. In this way, Galileo was accused of contradicting the fathers of the Church and nothing less than the Scriptures, which at no time questioned that the Earth was not at the center of the universe. This was how the court closed the case and ruled with an unappealable sentence.
The dramatic abjuration
Seven of the ten members of the court ruled in favor of Galileo’s guilt, which shows us that there was no absolute consensus and that there were probably heated debates in those deliberations, of which we have no record. The ruling found Galileo guilty of the charge of heresy and sentenced him to prison, which the Pope hastened to commute to house arrest for life. However, the sentence provided for a second punishment that we can imagine, with almost absolute certainty, would make Galilei angrier than imprisonment. It was about the obligation to abjure their ideas , that is, to publicly deny them. Galileo had dedicated a large part of his life to heliocentrism, especially since he began to study the stars with his telescope. We can understand, then, how much it must have cost him to say —after a long process that diminished his health and affected his once indomitable character— those words that he was forced to pronounce: «I, Galileo, son of Vincenzo Galilei, 70 years old age, I swear that I have always believed, believe and will believe in the future with the help of God in everything that the Holy Church upholds, preaches and teaches. After being admonished by this Holy Office, I abandon entirely the false opinion that the Sun is the center of the Universe and that it is an immovable star and that the Earth is not the center of it, but is a moving star.
The dramatic cause of the Church against Galileo Galilei exemplifies like no other event the confrontation between science and religion. However, in history there are plenty of examples of communion between both fields, with religious scientists ranging from Copernicus himself to Gregor Mendel (the father of genetics); therefore, the process of the great Pisan must not only be understood from a religious point of view. His cause was also that of someone who with stubborn self-sacrifice was able to question a ruling power for much of his life. Galileo not only left us a method to find the truth, but also the example of why we should pursue it.
