I have been criticised for claiming, in a recent post, that given time the Catholic Church would have come to accept heliocentricity in the seventeenth-century and in fact because Galileo acted unadvisedly he drove the Church to reject and condemn heliocentricity and thus to substantially delaying its acceptance by that organisation. The criticism was that this claim is speculative and thus not history and one critic even said not scientific. Point one, history is not science and is considerably more speculative than science, although, contrary to popular opinion, science is by no means free of speculation. In this case I think a certain amount of speculation is justified and by looking at the available facts on the attitudes of Catholic astronomers, and in particular the Jesuits, during the seventeenth-century both before and after the events of 1615, which will be discussed, it is possible to argue for a Catholic acceptance of heliocentricity, if Galileo and Foscarini had not driven the theologians into a corner causing them to reject it.

In the first seven decades following the publication of Copernicus’ De revolutionibus there was almost no rejection of heliocentricity on religious grounds but also very little acceptance by astronomers because of the substantial scientific problems that the theory entailed; problems associated with the physics of a moving earth. In a notorious footnote Copernican expert, Robert Westman, pointed out that there were only ten Copernican in the whole world between the publication of De revolutionibus in 1543 and 1600 and not all of those were astronomers, although it did include both Kepler and Galileo. After an initial period of excitement following the books publication Copernicanism was slowly drifting into obscurity due to its failure to deliver the goods, accurate astronomical tables. This situation changed dramatically in 1609.

In 1609 Kepler published his Astronomia Nova containing his first two laws of planetary motion based on solid empirical evidence supplied by Tycho Brahe and providing the best evidence for a heliocentric system by that time. The same year also saw the advent of telescopic astronomy, the telescope having been invented in the previous year, and the beginning of a series of astronomical discoveries by Thomas Harriot, Simon Marius, Galileo Galilei, and the Jesuit astronomers Odo van Maelcote, Giovanni Paolo Lembo and Christoph Grienberger that brought about the biggest changes in astronomy since human being first turned their gaze to the heavens; most notably Galileo published his initial discoveries in his Sidereus Nuncius in 1610. None of these discoveries proved heliocentricity but they did refute significant aspects of the accepted Aristotelian cosmology and the Ptolemaic geocentric astronomy forcing a serious and deep re-alignment of both disciplines. It was the Church’s own astronomers from the Jesuit Collegio Romano, who had quietly been making their own observations and discoveries before the publication of Sidereus Nuncius, who provided the much needed scientific confirmation of Galileo’s discoveries; passing this information on to the Church’s theologians. The Jesuit astronomers fully aware that Ptolemaic geocentricity was no longer tenable, following the discovery of the phases of Venus, like most other European astronomers, adopted the Tychonic helio-geocentric system; an intermediate solution that combined the best technical aspects of heliocentricity, for example the explanation of retrograde motion, without moving the earth. This was an important step down the road to heliocentricity, especially if, as it often was, combined with diurnal rotation. However Galileo could not accept this rational compromise, his ambition drove him on, because he wanted to go down in history as the man who established heliocentricity, ignoring in his egotism the work of Kepler who was much more advanced in his heliocentric astronomy than Galileo himself. To understand what happened next we need to briefly examine the position of the Church in this situation.

Religions are by their very nature conservative and opposed to sudden or significant change. They claim to be purveyors not just of truth but ‘the’ truth. This being the case all change is in one way or another an admission of failure; we got it wrong! This does not mean that religions are never changing, frozen in time, but it does mean that all change should be gradual, controlled and fully explainable within the religion’s own model of reality. A religion cannot allow itself to be seen to be forced to change by outside forces, otherwise believers might begin to question their monopoly on the truth. Since the thirteenth-century the Catholic Church had integrated an uneasy synthesis of Aristotelian cosmology and Ptolemaic astronomy, largely created by Albertus Magnus and his pupil Thomas Aquinas, into their model of reality, one that seemed to fit the known empirical facts. Now at the end of the first decade of the seventeenth-century this synthesis was crumbling away very fast and the Church was in a very dodgy situation, over which they had very little control, a potential nightmare for the theologians, the official purveyors of the truth. The central problem in this situation was that various passages in the Bible, supposedly the indisputable word of God, contradicted a heliocentric model with a stationary sun and a mobile earth, most notably Joshua 10:12 “…and he said in the sight of Israel, Sun, stand thou still upon Gibeon; and, Moon, in the valley of Ajalon”. If the sun wasn’t moving how could the Lord command it to stand still? The Church’s theologians were not stupid and it was very clear to them that if they accepted heliocentricity then they would have to abandon a literal interpretation of this and some other passages in the Bible; a change that they were only prepared to make if there was solid empirical evidence available to make it inevitable, as we will see.

By 1613 Galileo was chomping at the bit and was very egger eager to persuade the whole world, including the Church, to accept Copernican heliocentricity. His influential friends within the Church, who included Cardinal Maffeo Barberini the future Pope Urban VIII, were very much aware of the situation sketched above and warned Galileo that he should proceed with caution and not stir up trouble with the Church’s theologians. Galileo ignored this very sensible advice. The matter first came to a head with the so-called Letter to Castelli that in a modified form is better known as the Letter to Christina. How this came about we need to look at Galileo’s official function at the Medici Court in Florence.

Galileo had used the Sidereus Nuncius to acquire a position at the Medici Court dedicating the pamphlet to Cosimo II, his former mathematics pupil, and naming the Moons of Jupiter, his greatest discovery, the Medicean Stars in his honour. This followed lengthy correspondence with court officials as to which name would be most acceptable to the Grand Duke. Galileo’s efforts were rewarded with a position as court philosophicus and mathematicus and an appointment as professor of mathematics at the University of Pisa without teaching obligations, all for a very generous salary. What exactly was Galileo’s role as court philosophicus? The position sounds very impressive but in reality, within the structure of a Renaissance absolutist court, Galileo was a sort of intellectual court jester. In an age without Internet, radio, television or any of the other modern invention with which we waste our time, after dinner entertainment at a Renaissance court took various forms; one of these took the form of intellectual debates. Galileo was expected to entertain the dinner guests by disputing given philosophical or scientific themes with others, especially invited for the purpose. Cosimo and his guest were not particularly concerned who won a given debate or who was right, they were more interested in being entertained by clever and witty repartee, Galileo a brilliant polemicist was naturally a master at this game and more than earned his keep. The situation that led to Galileo writing the Letter to Christina actually took place in Galileo’s absence.

Late in 1613 the newly appointed professor of mathematics at the University of Pisa, Benedetto Castelli, a pupil of Galileo’s, attended a lunch hosted by the Grand Duchess Christina, Galileo’s earlier patron who had employed him to teach mathematics to Cosimo. Also present on this occasion was the Pisan professor for philosophy, Cosimo Boscaglia. Christina expressed doubts about the existence of the Moons of Jupiter and about their possible connection with the, in her eyes, heretical Copernican astronomy. Boscaglia assured her that the moons were indeed real and expressed similar doubts about their astronomical implications. After the meal Christina summoned Castelli to her chamber and in the presence of Boscaglia and other guests challenged him on the mobility of the earth. Castelli was in the hot spot, but according to his own account, in a letter to Galileo, he acquitted himself skilfully. Galileo now set in motion a chain of events that probably constitute the biggest error in his life. He wrote a long letter to Castelli supplying him with arguments to use against those quoting Bible passages against heliocentricity. He set about playing the theologian, reinterpreting those passages to make them conform to Copernican thought. He suggested for example that when the Lord commanded the sun to stand still he stopped its rotation about its axis, a rotation that Galileo had recently proved with his study of sunspots. The whole letter was, to put it mildly, a blunder.

Some of Galileo’s enemies, disgruntled Aristotelians who had been subjected publically to the scorn of Galileo’s sharp tongue, got hold of a copy of the letter and presented it to the Church authorities. Surprisingly the Church found most of the letter unobjectionable except for a handful of passages. Galileo tried to bluff his way out of the matter by claiming that those passages were not in the original but had been added to the copy by his enemies, whether you believe him or not is left entirely up to you. The Church demanded the original. In the meantime Galileo instead of backing down was working on an expanded version of the letter, which would go down in history as the Letter to Christina, to whom it was directly addressed. Galileo really did not know when to leave things alone. Why one might ask was it so terrible for Galileo to suggest new interpretations of the Bible?

The Catholic Church was founded on the premise that they, and they alone, were privileged to interpret the word of God. In the early sixteenth century various thinkers, who became known collectively as the Protestants, challenged the Church on this very issue, claiming that every individual had the right to read and interpret the word of God for himself. A universal claim that was later modified as the various branches of this protest movement solidified into established churches themselves. But I digress. This led to the greatest schism in Church history now known as the Reformation. From the middle of the century following the Council of Trent the Catholic Church hit back with its own movement, which became known as the Counter-Reformation, leading storm-troopers being the Jesuits, although they were not initially founded for this purpose. Galileo, a mere mathematicus and thus the lowest of the low in the intellectual hierarchy, was claiming the right to re-interpret the Bible just five years before the outbreak of the Thirty Years War the devastating and extremely bloody highpoint of this struggle between the forces of Reformation and Counter-Reformation. Not a clever move from a man who many regard as a genius.

To pour even more oil into the fire, as if Galileo’s own efforts were not enough, a Carmelite theologian, Paolo Antonio Foscarini, submitted a book he had written to the Church censors in 1615, which contained very similar reinterpretations of the Bible to bring it into line with the Copernican heliocentric hypothesis. Not surprisingly the anonymous censor thought the book to “excessively favour the rash opinion” of Copernicus. Like Galileo, Foscarini was not prepared to let matter lie and submitted both the text of his book and the censor’s judgement to the Jesuit Cardinal Roberto Bellarmino, who was considered one of the greatest living theologians. Bellarmino considered Foscarini’s book and Galileo’s letter and came to a famous conclusion that he sent to Foscarini in the form of a letter the relevant passages of which I have reproduced below.

My Very Reverend Father,

It has been a pleasure for me to read the Italian letter and the Latin paper you sent me. I thank you for both the one and the other, and I may tell you that I found them replete with skill and learning. As you ask for m y opinion, I will give it as briefly as possible because, at the moment I have very little time for writing.

First, I say it seems to me that your Reverence and Signor Galileo act prudently when you content yourselves with speaking hypothetically and no absolutely, as I have always understood that Copernicus spoke. For to say that the assumptions that the Earth moves and the Sun stands still saves all the celestial appearances better than do eccentrics and epicycles is to speak with excellent good sense and to run the risk whatever. Such a manner of speaking suffices for a mathematician. But to want to affirm that the Sun, in very truth, is at the centre of the universe and only rotates on its axis without traveling from east to west, and that the Earth is situated in the third sphere and revolves very swiftly around the Sun, is a very dangerous attitude and one calculated not only to arouse all Scholastic philosophers and theologians but also to injure our hold faith by contradicting the Scriptures….

Second, I say that, as you know, the Council of Trent forbids the interpretation of the Scriptures in a way contrary to the common agreement of the holy Fathers. Now if your Reverence will read, not merely the Fathers, but modern commentators on Genesis, the Psalms, Ecclesiastes, and Joshua, you will discover that all agree in interpreting them literally as teaching that the Sun is in the heavens and revolves round the Earth with immense speed and that the Earth is very distant from the heavens, at the centre of the universe, and motionless. Consider, then in your prudence, whether the Church can support that the Scriptures should be interpreted in a manner contrary to that of the holy Fathers and of all modern commentators, both Latin and Greek….

Third, I say that, if there were a real proof that the Sun is in the centre of the universe, that the Earth is in the third sphere, and that the Sun does not go round the Earth but the Earth round the Sun, then we should have to proceed with great circumspection in explaining passages of Scripture which appear to teach the contrary, and we should rather have to say that we did not understand them than declare an opinion to be false which is proved to be true. But I do not think there is any such proof since none has been shown to me. To demonstrate that the appearances are saved by assuming the sun at the centre and the earth in the heavens is not the same thing as to demonstrate that in fact the sun is in the centre and the earth is in the heavens. I believe that the first demonstration may exist, but I have very grave doubts about the second; and in case of doubt one may not abandon the Holy Scriptures as expounded by the hold Fathers…

Having very firmly pointed out that neither Galileo nor Foscarini had the right to interpret or reinterpret Holy Scripture, Bellarmino adds a very important comment in the final paragraph. He states very clearly that if there were proof of the heliocentric system then the Church would have to very carefully reinterpret the Bible, but he says, quite correctly, such proof does not exist at the moment so no deal. He then goes on the say that he personally doesn’t think that such proof would ever be found, proving that even Saint Roberto Bellarmino S. J. was not infallible. This final passage clearly illustrates something that the modern Galileo fan club love to ignore; in 1615 there was no empirical proof for the heliocentric hypothesis. It has been suggested that some Jesuit astronomers interpreted Bellarmino’s concession that if such a proof were to be found, as an instruction to go out and find one, but more of that in Part 2 – the consequences.

Things were now approaching the denouement. It was very clear to Galileo and all the other interested parties that the whole episode had been submitted to the Roman Inquisition. Instead of doing the sensible thing and keeping his head below the parapet, as advised by all of his influential friends including Cesi the head of the Academia dei LIncei and Cardinal Barberini, Galileo decided to go on the offensive. Obtaining permission from his employer, Cosimo, Galileo set off to Rome to canvas for the acceptance of heliocentricity. Knowing full well that he lacked empirical proof of heliocentricity, Galileo wrote up for the first time his infamous theory of the tides, thought out by him and Paolo Sarpi in the 1590s and which would go on to become Day Four, the crowning glory as he saw it, of his Dialogo. This theory posited that the tides were the result of the oceans swapping about like water in a moving bowl, as a result of the motion of the earth. It suffered from one major failure, and lots of minor ones, it only allowed for one tide a day, whereas there are in reality two.

Galileo arrived in Rome and began badgering anybody and everybody of influence that he could get hold off pressing copies of his theory of the tides into their hands and trying to persuade them to support his cause. He might as well have stayed at home, nobody in Rome, least of all influential public figures, was going to stick his neck out and help a mere mathematicus who was under investigation by the Inquisition.

It came as it had to come, the eleven members of the commission set up to adjudicate on the affair found that the idea that the Sun is stationary is “foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture…”; while the Earth’s movement “receives the same judgement in philosophy and … in regard to theological truth it is at least erroneous in faith.” Put into simple terms heliocentricity, as a theory of fact was both scientifically and theologically wrong. Galileo and Foscarini had forced the Church into making, what was to all intents and purposes, a disastrous judgement. As everybody knows the Pope instructed Bellarmino to inform Galileo of the commission’s judgement and to formally forbid him from holding or teaching the heliocentric theory. It is important to note that the theory, heliocentricity as a statement of fact, was forbidden and not the hypothesis, a distinction that was to play a very central role in the following decades.

Personally, this judgement had very little influence on Galileo life or status in Northern Italian society. Initially there were some rumours that he had been punished in some way by the Church, but at Galileo’s request Bellarmino wrote a letter stating that they had merely had a friendly chat and that Galileo was free of all suspicion. Unfortunately Galileo would later view this letter as a get out of gaol free card but that is the subject of another story. Galileo continued to be a highly feted figure in Northern Italian intellectual circles and to have easy access to the highest circles of the Church. He was not some sort of outcast battling the ignorant Curia, as he is often falsely depicted.

The direct consequences for the heliocentric hypothesis were that Foscarini’s book together with the books of the Protestant Copernicans, Michael Maestlin and Johannes Kepler were placed on the Index of Forbidden Books. Interestingly De revolutionibus was only placed on the Index until corrected. What this meant and the effect that all of this on the future development of heliocentricity will be dealt with in Part 2 – the consequences, which should, all thing being well appear here next week.

For those reading one of my The Transition to Heliocentricity: The Rough Guides posts for the first time you can find a list of links at the top of the website.