The Greatest Scandal in Christendom,
an essay on Galileo,
by Arthur Koestler

Last modified: 24 Nov 2008, 12:40-0500

Posters' Note

This essay was taken from:
     "Drinkers of Infinity: Essays 1955-1967", The MacMillan Company, 1969, pp. 18-38.
It was scanned, and therefore undoubtedly contains errors, which we encourage you to report.

The Greatest Scandal in Christendom (1)

`Alas,' the old man of seventy-three wrote to his admirer, Diodati, `your friend and servant Galileo has been for the last month hopelessly blind; so that this heaven, this earth, this universe, which I, by marvellous discoveries and clear demonstrations, have enlarged a hundred thousand times beyond the belief of the wise men of bygone ages, hence forward for me is shrunk into such small space as is filled by my own bodily sensations....'

All the main ingredients are there, contained in a few lines: the grandeur, the boastfulness, the self-pity, the elegance of style.

The letter is dated from Galileo's villa, Il Giojello, at Arcetri where he spent the last years of his life. It stands on a hill among olive groves overlooking Florence, but its name, the jewel, sounds today sadly ironical. The garden, where he received Milton and a stream of other celebrities, is covered with weeds; the sixteenth-century house, with its old beams and high ceilings, is occupied by tenants and contains no trace of the past. On the outside of the massive stone wall which separate the garden from the one and only street of the village of Arcetri, there is a sort of niche containing an old marble pissoir without a door or screen; close to it is a decayed memorial plaque with a bust of Galileo sternly watching the urinators. Whether this is intended as a deliberate insult -- a kind of Clochemerlc in reverse -- I was unable to discover; but it certainly testifies to a lack of reverence of the powers that be towards the memory of the man who, in the words of his one-time admirer, Pope Urban VIII, had `given rise to the greatest scandal throughout Christendom'. Its shadow still lingers over the desolate house.

The scandal is one of the historic causes which made post-Renaissance Europe a divided house of faith and reason. Legend has turned Galileo into a martyr of the freedom of thought, Urban into its benighted oppressor, and the conflict into a kind of Greek tragedy ennobled by the stamp of historical inevitability. In fact it was a clash of temperaments wantonly provoked and aggravated by unlucky coincidences.

To understand what really happened, a word must be said about the background -- the grand topography of the universe, as Galileo's contemporaries saw it.

For the last two thousand years, according to the orthodox doctrine, the solid earth had been regarded as the centre of the world round which the sun, the planets and the stars revolved in their orbits; it was based on the legacy of Aristotle and had been elaborated in detail by Ptolemy, an Alexandrian astronomer of the second century A.D. As against this there existed another grand scheme of even more ancient origin. The Pythagorean school, which had flourished between the fifth and third centuries B.C., had taught that the earth rotated on its own axis; and at least one Pythagorean, Aristarchus of Samos, held that in addition to its daily rotation, the earth also travelled through space in its annual revolutions round the sun; the five known planets did the same, so that the sun, and not the earth, was the centre and hub of the universe.

The geocentric system of Aristotle and Ptolemy had prevailed, but the rival heliocentric system of the Pythagoreans was never quite forgotten. It was preserved in the writings of the Latin compilers; it was finally revived and elaborated in detail by Canon Koppernigk or Copernick, called Copernicus, a somewhat crotchety cleric in the God-forsaken province of Varmia on the Baltic Sea.

Copernicus had died in 1543 twenty-one years before Galileo was born; his book, On the Revolutions of the Heavenly Spheres, which outlined the heliocentric system, was published in the last year of his life. For more than half a century it aroused very little interest. It was addressed, as the title page said, `to mathematicians only', it was clumsily written, and marred by inconsistencies. The reaction of the academic world was, with a few exceptions, indifferent or hostile, as Copernicus had feared; it was this fear `to be laughed at and hissed off the stage' (to quote his own words) which had caused him to withhold publication of the Book of the Revolutions until the end of his life.

What made him finally overcome his apprehensions were the urgent entreaties of his superiors in the ecclesiastical hierarchy who had read manuscript outlines of his theory. In 1533 Pope Clement VII had listened to a lecture on the Copernican theory, and was favourably impressed; a few years later, Cardinal Schönberg, who occupied positions of special trust under three successive Popes, wrote to the humble canon in Varmia that he had learned with great admiration about Copernicus' `having created a new theory of the Universe according to which the Earth moves and the sun occupies the basic and central position.... Therefore, learned man, without wishing to be inopportune, I beg you most emphatically to communicate your discovery to the learned world....'

Copernicus printed the letter as a preface to his book, which he dedicated to Clement's successor, Paul III. Thus, contrary to legend, the Church did not initially oppose the theory of the motion of the earth. The opposite is true. Without the encouragement and patronage of the clergy -- from the Bishop of Varmia to circles close to the Vatican -- Canon Copernicus' book would never have seen the light of day. Nor did the attitude of the Church change for the next eighty years.

Galileo became converted to the Copernican system in his twenties. But he kept his convictions secret until he was nearly fifty, although he had no more reason to fear religious persecution than Copernicus had. Through all these years he taught in his lectures the old astronomy of Ptolemy, and expressly repudiated the earth's motion by means of the traditional arguments (the clouds would be left behind, etc.) which he knew to be false. This fact is passed over in silence by Galileo's biographers, although it is an important clue to his character.(2)

The reason why he kept his opinions so carefully concealed was the same as in Copernicus' case: the fear of ridicule by his narrow-minded colleagues who occupied the chairs of astronomy in Bologna, Pisa, Padua and elsewhere. In a letter to the German astronomer, Johannes Kepler (the first to raise his voice in public for Copernicus, fifteen years before Galileo), he confessed: `I have not dared to bring my views into the public light, frightened by the fate of Copernicus himself, our teacher, who, though he acquired immortal fame with some, was yet by an infinite multitude of others -- for such is the number of fools -- laughed at and hissed off the stage.' The risk of ecclesiastic censure did not even occur to him because, during the first fifty years of his lifetime, no such risk existed. Even his latest apologist, Giorgio de Santillana, admitted: `On his [Galileo's] own account, he knew the Jesuits as modern-minded humanists, friends of science and discovery. Those he feared were the professors.'(3) And that fear, as events proved, was fully justified.

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In 1610 when he was forty-six, Galileo's life took a dramatic turn. He was then Professor of Mathematics in Padua, much admired by his friends for his revolutionary researches in physics -- which he communicated to them in private letters -- but as yet untouched by public fame. Fame came almost overnight through his astronomical discoveries, made possible by that newly invented gadget, the telescope. It was invented by a Dutchman, but Galileo built his own instruments with a vastly improved magnifying power. He published his observations in a booklet' Siderius Nuncius -- the `Star Messenger'. It described the mountainous configurations of the moon, the dissolution of the Milky Way into `a map of unnumerable stars planted together in clusters', and left the most momentous news to the last -- that the planet Jupiter possessed four moons `never seen from the beginning of the world up to our times'. This did not prove that the Coperni- can scheme of the universe was right, but it shattered the orthodox doctrine that the earth was the centre of the world around which everything revolved -- the Jupiter moons danced attendance to a rival body.

The `Star Messenger' created a sensation. Cardinal del Monte, one of Galileo's patrons, wrote in a letter: `If we were still living under the ancient Republic of Rome, I verily believe that there would be a column on the Capitol erected in Galileo's honour.' The Jesuits of the Roman College, who were the leading astronomers of the day, bestowed ceremonial honours on him; Pope Paul V received him in a long audience. Yet barely five years later an edict of the Holy Office condemned the Copernican theory as incompatible with Holy Scripture, and Galileo was enjoined, by order of Pope Paul, not to `hold or defend' it.

On whom does the historic responsibility rest? In the first place on `the professors', the academic mediocracy, who hated Galileo, partly out of jealousy, partly because they were the rearguard of those Schoolmen whom Erasmus had accused of `looking in utter darkness for that which has no existence whatsoever'. They were so dazzled by what the telescope revealed that several of them, like the illustrious Cremonini, refused on principle to look through it; and those who did look pretended that the Jupiter-moons were optical illusions. But eventually the `Pigeon League' -- as Galileo contemptuously called them after their leader, Lodovico delle Colombe -- had to accept defeat, when the élite of the Jesuit astronomers at their observatories in various parts of Europe not only confirmed Galileo's discoveries, but improved on them.

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At this point Galileo's vanity played him a trick which had disastrous results. For more than twenty years he had believed in the Copernican system but had taught the opposite. Now, encouraged by his success, he had come out into the open; and once he had committed himself to the Copernican theory anybody who opposed it was to be regarded as a `mental pygmy', `hardly deserving to be called a human being'.

But he had no scientific proof that the Copernican system was correct. The point is somewhat technical, but basic to the understanding of the whole drama. The Jupiter moons and other phenomena proved that Aristotle had been wrong -- they did not prove that Copernicus had been right. There existed alternative possibilities -- such as the compromise system of Tycho de Brahe, in which the planets revolved round the sun, and the sun round the earth. It was a half-way house, but from the point of view of mathematical calculation just as satisfactory as the Copernican system -- and the available data spoke in favour of Tycho and against Copernicus. For if the earth really moved round the sun, then its position relative to the fixed stars must differ by nearly two hundred million miles every six months, and their constellations ought to expand and shrink according to whether the earth approached or receded from them. But in spite of the thousandfold magnification of Galileo's telescopes, no such effect was found (it was only found two centuries later by Bessel). Thus not only tradition, prejudice and naïve `commonsense', but also the scientific evidence available at the time, spoke against the Copernican theory.

Galileo was well aware of this. So were his enemies. But since they had been defeated in the controversy on the Jupiter moons and in several other disputes, they knew they were no match either for his genius or his polemical brilliance. So the Pigeon League shifted its ground from science to theology. They produced quotations from Holy Scripture in refutation of Copernicus. Thus Joshua, after defeating the Philistines, had cried `Sun, stand thou still' -- which proved clearly that it was the sun which moved, not the earth.

Galileo fell into the trap. In two treatises, which he circulated widely in manuscript copies (`Letter to Castelli', 1613 enlarged a year later into `Letter to the Grand Duchess Christina'), he dived headlong into theology. He evaded any scientific discussion of the Copernican system by simply pretending that it was proven beyond doubt; proposed that biblical passages which contradicted it should be re-interpreted, and insisted that the Church must either endorse the Copernican theory or condemn it altogether. This made a showdown unavoidable.

Galileo's friends in the upper ranks of the Church hierarchy -- foremost among them Maffeo Barberini, the future Pope -- did everything in their power to avoid the showdown. When the monks of St. Marco in Florence denounced the `Letter to Castelli', the Holy Office dismissed the case. When a Dominican by the name of Caccini attacked Galileo from the pulpit, the Preacher General of the Order promptly wrote him a letter of apology. The official attitude of the Church was summed up by its highest theological authority: Cardinal Bellarmine, General of the Jesuit Order, Consultor to the Holy Office (the `devilish Jebusite' whom the English suspected of having instigated the Gunpowder Plot). In a letter to Father Foscarini, a Carmelite monk who had just published a book advocating the Copernican system, but equally addressed to Galileo, who is mentioned by name, Bellarmine explained that to teach the Copernican system as a working hypothesis superior to Ptolemy's `is to speak with excellent sense and to run no risk whatever. Such a manner of speaking suffices for a mathematician.' But to speak of it as an established truth `is a very dangerous attitude and one calculated not only to arouse the Scholastic philosophers and theologians, but also to injure our holy faith by contradicting the Scriptures'. However, Bellarmine continued, if there existed a `real proof' which `truly demonstrated' the earth's motion, then the relevant passages in the Scriptures would have to be re-interpreted. `But I do not think there is any such proof since none has been shown to me.'

Bellarmine's ruling reflected not only the established practice of the Church in such matters; its substance would also have been endorsed by any responsible body of modern empirical scientists. But Galileo was past reasoning. To admit that the Copernican system was no more than an unproven hypothesis, however excellent, would amount to the confession that he had no evidence to offer, and expose him to the ridicule of his opponents. There is hardly a more frustrating experience for a scientist than to know that one is right, but to be unable to prove it -- and to be `hissed off the stage' by an audience of imbeciles. Against the warnings of Bellarmine and other friendly cardinals, Galileo rushed to Rome, to force a decision. `He is passionately involved in this quarrel' the Tuscan Ambassador reported, `so that he will be snarled in it and get himself into danger.... For he is vehement and all impassioned in this affair.'

He tried unsuccessfully for an audience with Paul V, who (as the same Ambassador described him) `abhors the liberal arts and cannot stand these novelties and subtleties'. Which particular incident brought matters to a head is still a matter of controversy, and without much importance. Galileo had insisted on a showdown; he had gambled and lost.

On March 5, 1616 the Holy Offlce issued a decree in which `the Pythagorean doctrine of the motion of the earth' was declared to be `false and altogether opposed to Holy Scripture'; to prevent its further spreading, Copernicus's Book of the Revolutions was `suspended until it be corrected'. It actually remained on the Index for no more than four years; the corrections consisted in the change or omission of altogether nine sentences in which the heliocentric system was represented as a certainty instead of a hypothesis. Galileo's name was not mentioned in the decree, his works were not prohibited, and to save him from public humiliation the injunction not to hold or defend the Copernican doctrine was communicated to him privately. To sweeten the pill even more, a week after publication of the decree, the Pope received Galileo in a long audience.

Thus the first act of the scandal ended on a decorous note; yet it injected a poison into the atmosphere of our culture which is still there. Act II came seventeen years later.

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The main event of the intervening years was the election to the Papacy of Galileo's most ardent admirer, Cardinal Maffeo Barberini. He had opposed the decree of 1616; he had written an ode in honour of Galileo; when he became Pope, he gave Galileo a testimonial extolling the virtues and piety `of this great man, whose fame shines in the heavens and goes on earth far and wide'. In 1624, a year after he had been installed as Urban VIII, he gave Galileo six long audiences in six weeks, showering gifts and favours on him.

Maffeo Barberini was a brilliant, vainglorious cynic who did not care much whether Copernicus contradicted the miracle of Joshua or not. On learning of Richelieu's death, he coined the famous epigram: `If God exists, Cardinal Richelieu will have much to answer for; if not, he has done very well.' His vanity was as monumental as Galileo's; he professed `to know better than all cardinals put together' as Galileo professed to be the `sole discoverer of all celestial novelties'. It needed no great psychiatric insight to predict the end of the affair.

Though Urban could not revoke the edict of 1616, he paid homage to the memory of Copernicus; and after those six long audiences, Galileo returned from Rome to Florence, reassured that he could now expound the Copernican system on condition that he stuck to the established rules of the game: to avoid theological arguments, and to speak of the earth's motion as a convenient working hypothesis without asserting that it was actually true.

This sounds reasonable enough. But Galileo's temperament made it impossible for him to abide by the rules -- and on this point every writer with strong convictions must sympathise with him. Besides, he thought that at long last he had found a physical proof for the motion of the earth (we remember that it was the lack of proof which had made him lose the first round of the battle). The proof was contained in his famous theory of the tides. Rejecting Kepler's correct suggestion that the tides were caused by the moon's attraction, Galileo had persuaded himself that the seas `swapped over' once a day as a direct consequence of the earth's motion. Here, then, was the evidence he had been so desperately looking for. It was a fallacy in such glaring contradiction to all the principles of the science of dynamics which he himself had discovered, and so unworthy of his genius, that it can be explained only as an idée fixe.

The years that followed were spent in writing his great apologia for the Copernican theory, the Dialogue on the Two Great World Systems. It is perhaps the most brilliant and exasperating work among the books which made history. Masterly expositions alternate in it with special pleading, immortal passages with cheap rhetoric and the deliberate falsification of facts. The theory of the tides occupies a central position, and serves to clinch the argument. Whatever the contemporary reader's reaction to the book, one point was made abundantly clear to him: that the earth's motion was not merely a working hypothesis but a fact so firmly established that it could be doubted only by `dumb moon-calves' whose stupidity `stains the honour of mankind'.

Thus the contents of the book were a flagrant contravention of the decree of 1616 and of the line agreed on with Urban VIII. But there were still other circumstances which precipitated the scandal. Galileo had obtained the imprimatur for the book by a series of manoeuvres which amounted to a confidence trick. He had antagonised his former supporters, the Jesuit astronomers, by laying unfounded priority claims to their discoveries, and engaging them in controversies on irrelevant subjects; it was as if he were acting under some self-destructive compulsion. Lastly, he had personally insulted the Pope. In the days of their mutual adulation, Urban had suggested an argument which would enable Galileo to speak favourably of the Copernican theory without asserting its actual truth. The argument was, briefly, that even if a hypothesis explains certain phenomena in a satisfactory manner, it need not necessarily be true, for God may have produced the same phenomena by different means, not comprehended by the human mind. This argument, to which Urban attached the greatest importance, is quoted only at the very end of the book; and the character who quotes it is Simplicio, the simpleton of the Dialogue, who has been shown up as a silly ass over and over again. Galileo might as well have stuck out his tongue in public at the Pope.

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Contrary to legend, Nemesis took a rather leisurely course. The book was published in February 1632. It was not until August that its sale was suspended, and a commission appointed to examine its contents. The commissioners indicted it on eight counts, but concluded that `all these matters could be corrected if it is decided that the book is of any value'. The report was then handed over to the Inquisition, which, in October, summoned Galileo to Rome. Galileo sent a medical certificate from Florence, attesting that he was suffering from `attacks of giddiness, hypochondriacal melancholy, weakness of stomach, insomnia, and flying pains about the body'; he thus succeeded in delaying his journey till February 1633. In Rome, he took up quarters in the Villa Medici, which was then the Tuscan Embassy, and another three months passed before he was summoned for his first interrogation by the Commissary of the Inquisition, Firenzuola.

From April 12 to May 10 while the proceedings lasted, he was formally a prisoner of the Inquisition; in fact he occupied a five-room flat in the Holy Offlce overlooking the Vatican Gardens, shared by his valet, while the Tuscan Ambassador's majordomo looked after his food and wine. He never spent a day of his life in a prison cell, and was neither tortured nor in fear of torture -- which, according to the rules of the Roman Inquisition, could not be inflicted on a man of his age. (The Spanish Inquisition was, of course, an altogether different matter.)

In short, the authorities treated Galileo with all the lenience and regard due to the foremost scholar of his time; and with that disregard for the freedom of thought which was engrained in their tradition and doctrine. They did not intend to turn him into a martyr, but rather to show that he was not of the stuff of which martyrs are made; to humiliate him, make him recant, and prove that not even a Galileo could allow himself to mock the Pope and challenge the authority of the theologians.

The legal proceedings were highly unorthodox. In the very first interrogation Galileo manoeuvred himself into an impossible position by pretending, in the teeth of the printed evidence, that his book was written with the intention not to support but to refute the Copernican theory. The only possible explanation of this folly is a failure of nerve. He had thought himself capable of outwitting Urban and everybody else; on being found out he realised that the game was up and he panicked.

Nothing happened for a fortnight. Then Firenzuola went on a private, `extrajudicial' visit to Galileo's apartment, and had no great difficulty in persuading him to make a deal. Soon afterwards he was allowed to return to the Villa Medici; another month later, on June 22, Galileo was conducted to a hall in the Convent of Santa Maria sopra Minerva, where in the presence of his judges -- ten Cardinals, only seven of whom had concurred -- the sentence was read out to him. The Dialogue was to be prohibited; to clear himself from the suspicion of heresy he was to recite a prepared text cursing and abjuring the doctrine of the earth's motion; and he was to be committed to `formal prison during the Holy Offlce's pleasure'. Then the vain old man went down on his knees before the venal Cardinals, recited a text in which nobody believed, wisely refrained from saying eppur si muove and the show-trial was over.

`Formal prison' meant, first, a sojourn with the Grand Duke of Tuscany, then with the Archbishop of Siena, followed by ten peaceful and creative years in the villa at Arcetri, where he wrote his masterpiece, the Dialogue Concerning Two New Sciences. It became one of the cornerstones of the Scientific Revolution, and made Galileo rank among the intellectual giants who shaped the destiny of the world.

His true greatness rests on achievements which have nothing to do with the Galileo legend. He never dropped cannonballs from the leaning tower of Pisa, made no contribution to theoretical astronomy, and did not prove the earth's motion. His real achievements are those found in every schoolbook: the laws of the pendulum, of free fall, of the flight of projectiles, of the elasticity, cohesion and resistance of solid bodies, and a hundred related matters. He was a pioneer of the experimental method and transformed physics into an exact, mathematical science. This was his vocation; not the ill-starred propaganda crusade based on fallacious arguments, which cost him twenty years of his life and ended in disaster.

It nearly put an end to three centuries of that peaceful coexistence between faith and reason which had started with Thomas of Aquinas, and saw Franciscans, Dominicans, Jesuits successively take the lead in the revival of learning, and the advance of science. Throughout the golden age of humanism and well into the seventeenth century, scientists like Copernicus and Galileo were the protégés of cardinals and popes; and the exploration of the laws of nature was regarded as a form of worship of the Supreme Mathematician.

The Galileo scandal marked a turning point -- a hardening of the fronts, the polarisation of rigid orthodoxies. The point I have been trying to make is that the blame was not all on one side; that the presumption of the theologians was matched by the hubris of an unbalanced genius and the vindictiveness of a benighted academic coterie. And concerning the latter, though methods have changed, it can hardly be said that behind the polite façades academic orthodoxy has become much more tolerant. The Inquisition at least has gone, and the Bishop of Woolwich has not been excommunicated; but the Pigeon Leagues are still flourishing in the Groves of Academe.

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1. First published in The Observer on the 400th anniversary of Galileo's birth, February 1964.
2. The proof is found in a surviving manuscript copy of a lecture by Galileo, dated 1606, Trattato della Sfera (Opere, Ediz. Nazionale, Florence; 1929-30, Vol. II, pp. 203-55).
3. The Crime of Galileo (Cambridge, 1955), p. 8.