Galileo delayed his answer for more than three months, and then claimed the priority of the discovery for himself. He alleged having observed sunspots for about eighteen months, and having shown them a year before "to many prelates and gentlemen in Rome", but did not name any of these witnesses.
In fact, the sunspots had been discovered independently and nearly at the same time by Johannes Fabricius in Wittenberg, Thomas Harriot in Oxford, Scheiner-Cysat, and Galileo himself. Harriot seems to have been the first to observe them, but Fabricius was the first to publish, and Scheiner the second. Harriott, Fabricius and Scheiner neither knew of the others' parallel discovery, nor did they raise any particular claim to priority. Thus Galileo's claim was untenable, firstly because Fabricius and Scheiner had been first to publish the discovery, and secondly because he could name no witnesses, or correspondents, to prove it – yet we remember how careful he was to protect his priority claims on previous occasions, by immediately sending out messages in anagram form. But Galileo had come to regard telescopic discoveries as his exclusive monopoly – as he himself stated on a later occasion:
"You cannot help it, Mr. Sarsi, that it was granted to me alone to discover all the new phenomena in the sky and nothing to anybody else. This is the truth which neither malice nor envy can suppress." 7
By his specious priority claim over the sunspots, followed by disguised attacks on Father Scheiner, Galileo had made the first enemy among the Jesuit astronomers, and started the fatal process which in the end would turn the order against him.
The whole affair was the more unfortunate, as Galileo's answer to Marcus Welser was otherwise a model of clarity and scientific method. He followed it up with two more Letters on Sunspots, which, the next year, were published under that title. He showed convincingly that the spots were not small planets circling the sun, as Scheiner had originally assumed, but located on, or close to, the surface of the sun itself; that they were rotating with the sun, constantly changing their shapes, and of the nature of "vapours, or exhalations, or clouds or fames." 8 Thus it was proven that not only the moon, but the sun too was subject to generation and decay.
The booklet also contained Galileo's first, tentative formulation of the principle of inertia, 8a and his first printed statement in favour of the Copernican system. Up to this date – we are now in 1613, and he is nearly fifty – he had defended Copernicus in conversations at dinner tables, but never in print. The passage in question is on the last page of the Letters on Sunspots; it starts with a reference to the alleged moons of Saturn and continues:
"And perhaps this planet also, no less than horned Venus, harmonises admirably with the great Copernican system, to the universal revelation of which doctrine propitious breezes are now seen to be directed toward us, leaving little fear of clouds or crosswinds." 9
Here it was at last, the first public commitment, though somewhat vague in form, a full quarter-century after Kepler had first sounded the Copernican trumpet in the Mysterium.
The book won immediate and great popular acclaim. Insofar as the Church is concerned, not only was no voice raised in opposition, but Cardinals Boromeo and Barberini – the future Urban VIII – wrote letters to Galileo expressing their sincere admiration.
Not so the backwoodsmen. When Galileo's favourite pupil, the Benedictine Father Castelli (the founder of modern hydrodynamics) was called to the chair of the University of Pisa, he was expressly forbidden by the head of the University to teach the motion of the earth. The head was Arturo d'Elci, a fanatical Aristotelian and member of the "Pigeon League", who had published one of the pamphlets against the Things that Float on Water.
The first serious attack against Copernicanism on religious grounds came also not from clerical quarters but from a layman – none other than delle Colombe, the leader of the league. His treatise Against the Motion of the Earth contained a number of quotations from Holy Scripture to prove that the earth was in the centre of the world. It was circulated in manuscript in 1610 or '11, before Galileo's public committal, and did not mention Galileo's name. Galileo himself was as yet so little worried about a possible theological conflict, that he had let almost a year pass before he asked the opinion of his friend, Cardinal Conti, on the matter. The Cardinal answered that, concerning the "immutability" of the skies, Holy Scripture seemed to favour Galileo's view rather than Aristotle's. As for Copernicus, the "progressive" (i.e. annual) motion was admissible, but the daily rotation did not seem to agree with Scripture, unless it was assumed that certain passages must not be taken literally; but such an interpretation was permissible "only in the case of the greatest necessity". 10
"Necessity" in this context meant once again: if and when convincing proof was shown of the reality of the earth's motion. But all this did not affect free discussion of the relative advantages of the Ptolemaic, Tychonic or Copernican systems as mathematical hypotheses.
There the matter could have rested, and probably would have rested, but for Galileo's hypersensitivity to criticism, and his irrepressible urge to get involved in controversy. Towards the end of 1612, he was staying in the villa, near Florence, of his friend Filippo Salviati (whom he immortalized in his two great Dialogues), when some gossip reached him to the effect that a Dominican Father, Niccolo Lorini, had attacked his views in a private conversation. Galileo immediately wrote to Lorini, asking for an explanation. Lorini was a gentleman of seventy, and professor of ecclesiastical history in Florence. He wrote back:
"I have never dreamt of getting involved in such matters... I am at a loss to know what grounds there can be for such a suspicion, as this thing has never occurred to me. It is indeed true that I, not with a desire to argue, but merely to avoid giving the impression of a blockhead when the discussion was started by others, did say a few words just to show I was alive. I said, as I still say, that this opinion of Ipernicus – or whatever his name is – would appear to be hostile to divine Scripture. But it is of little consequence to me, for I have other things to do..." 11
The next year, 1613, brought the publication of the "Sunspots", and general public acclaim; including, as mentioned, the future Pope's. All was sunshine. Then another piece of gossip reached Galileo, this time from Pisa. It concerned an after-dinner conversation at Duke Cosimo's table. This banal incident was the beginning of what became "the greatest scandal in Christendom".
3. The Shifting of the Burden
Faithful Father Castelli, now Professor of Mathematics at Pisa, the post from which Galileo had started his career, had been invited for dinner at Court. An illustrious company was present, including the Duke's mother, the Dowager Duchess Christina of Lorraine, his wife Madeleine of Austria, and several other guests, among them Dr. Boscaglia, a professor of philosophy.
The conversation was led by Madame Christina, who appears to have conformed to the idea of a bossy, talkative and scatterbrained Dowager. During dinner she felt the sudden urge "to learn all about" those Mediciean planets. First she wanted to know their positions, then whether they were real or just illusions. Both Castelli and Boscaglia solemnly confirmed that they were real. Soon after that, dinner was over, and Father Castelli left.
"But I had hardly come out of the palace when Madame Christina's porter overtook me and told me that she wished me to return," Castelli's report to Galileo continued. "Now before I tell you what ensued, you must first know that while we were at table, Dr. Boscaglia had had the ear of Madame for a while; and conceding as true all the new things you have discovered in the sky, he said that only the motion of the earth had something incredible in it, and could not take place, in particular because Holy Scripture was obviously contrary to this view."
When Castelli returned to the drawing-room, "Madame began, after some questions about myself, to argue Holy Scripture against me. Thereupon, after having made suitable disclaimers, I commenced to play the theologian and ... carried things off like a paladine." Everybody took the side of Castelli and Galileo, "only Madame Christina remained against me, but from her ma
nner I judged that she did this only to hear my answers. Professor Boscaglia never said a word." 12
In subsequent letters, Castelli reported that Boscaglia had once more been defeated in debate, that even the irascible Dowager had been won over, and that the subject had been dropped.
This, then, is the incident which touched off the drama. As on that previous occasion, when Lorini had remarked on "Ipernicus – or whatever his name is", Galileo was at once up in arms. His counter-blast to the dinner-table chirpings of the obscure Dr. Boscaglia (who is never heard of again), was a kind of theological atom bomb, whose radioactive fall-out is still being felt. It took the form of a Letter to Castelli, enlarged a year later into a Letter to the Grand Duchess Christina. It was intended to be widely circulated, which indeed it was. Its purpose was to silence all theological objections to Copernicus. Its result was the precise opposite: it became the principal cause of the prohibition of Copernicus, and of Galileo's downfall.
As a work of polemical literature the Letter is a masterpiece. It starts: *
"Some years ago, as Your Serene Highness well knows, I discovered in the heavens many things that had not been seen before our own age. The novelty of these things, as well as some consequences which followed from them in contradiction to the physical notions commonly held among academic philosophers, stirred up against me no small number of professors – as if I had placed these things in the sky with my own hands in order to upset nature and overturn the sciences...
Showing a greater fondness for their own opinions than for truth, they sought to deny and disprove the new things which, if they had cared to look for themselves, their own senses would have demonstrated to them. To this end they hurled various charges and published numerous writings filled with vain arguments, and they made the grave mistake of sprinkling these with passages taken from places in the Bible which they had failed to understand properly..." 13
____________________
*
I shall follow the final version of the document, i.e., the Letter to the Grand Duchess.
Galileo then developed the argument which Kepler, too, had constantly used, namely that certain statements in the Bible should not be taken literally because they were couched in language "according to the capacity of the common people who are rude and unlearned":
"Hence, in expounding the Bible, if one were always to confine oneself to the unadorned grammatical meaning, one might fall into error. Not only contradictions and propositions far from true might thus be made to appear in the Bible, but even grave heresies and follies. Thus it would be necessary to assign to God feet, hands, and eyes, as well as corporeal and human affections, such as anger, repentance, hatred, and sometimes even the forgetting of things past and ignorance of those to come... For that reason it appears that nothing physical which sense-experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question (much less condemned) upon the testimony of biblical passages which may have some different meaning beneath their words." 14
In support of this thesis, Galileo quoted at length St. Augustine as a witness – not realizing that, theologically, he was walking on extremely thin ice (see below, p. 443). Then comes a breathtaking passage, where one can almost hear the ice cracking under his feet:
"... I question whether there is not some equivocation in failing to specify the virtues which entitle sacred theology to the title of 'queen'. It might deserve that name by reason of including everything that is learned from all the other sciences and establishing everything by better methods and with profounder learning... Or theology might be queen because of being occupied with a subject which excels in dignity all the subjects which compose the other sciences, and because her teachings are divulged in more sublime ways.
That the title and authority of queen belongs to theology in the first sense, I think will not be affirmed by theologians who have any skill in the other sciences. None of these, I think, will say that geometry, astronomy, music, and medicine are more excellently contained in the Bible than they are in the books of Archimedes, Ptolemy, Boethius, and Galen. Hence it seems likely that regal pre-eminence is given to theology in the second sense; that is, by reason of its subject and the miraculous communication, by divine revelation, of conclusions which could not be conceived by men in any other way, concerning chiefly the attainment of eternal blessedness.
Let us grant then that theology is conversant with the loftiest divine contemplation, and occupies the regal throne among the sciences by this dignity. But acquiring the highest authority in this way, if she does not descend to the lower and humbler speculations of the subordinate sciences and has no regard for them because they are not concerned with blessedness, then her professors should not arrogate to themselves the authority to decide on controversies in professions which they have neither studied nor practised. Why, this would be as if an absolute despot, being neither a physician nor an architect, but knowing himself free to command, should undertake to administer medicines and erect buildings according to his whim – at grave peril of his poor patients' lives, and the speedy collapse of his edifices..." 15
While reading this superb manifesto of the freedom of thought, one tends to forgive Galileo his human failings. These, however, become only too apparent in the piece of special pleading which follows the passage I have quoted, and which was to have disastrous consequences.
After invoking Augustine's authority once more, Galileo draws a distinction between scientific propositions which are "soundly demonstrated" (i.e. proven) and others which are "merely stated". If propositions of the first kind contradict the apparent meaning of passages in the Bible, then, according to theological practice, the meaning of these passages must be reinterpreted – as was done, for instance, with regard to the spherical shape of the earth. So far he has stated the attitude of the Church correctly; but he continues:
"And as to the propositions which are stated but not rigorously demonstrated, anything contrary to the Bible involved by them must be held undoubtedly false and should be proved so by every possible means." 16
Now this was demonstrably not the attitude of the Church. "Propositions which are stated but not rigorously demonstrated," such as the Copernican system itself, were not condemned outright if they seemed to contradict Holy Scripture; they were merely relegated to the rank of "working hypotheses" (where they rightly belong), with an implied: "wait and see; if you bring proof, then, but only then, we shall have to reinterpret Scripture in the light of this necessity." But Galileo did not want to bear the burden of proof; for the crux of the matter is, as will be seen, that he had no proof. Therefore, firstly, he conjured up an artificial black-or-white alternative, by pretending that a proposition must either be accepted or outright condemned. The purpose of this sleight of hand becomes evident from the next sentence:
"Now if truly demonstrated physical conclusions need not be subordinated to biblical passages, but the latter must rather be shown not to interfere with the former, then before a physical proposition is condemned it must be shown to be not rigorously demonstrated – and this is to be done not by those who hold the proposition to be true, but by those who judge it to be false. This seems very reasonable and natural, for those who believe an argument to be false may much more easily find the fallacies in it than men who consider it to be true and conclusive..." 17
The burden of proof has been shifted. The crucial words are those in (my) italics. It is no longer Galileo's task to prove the Copernican system, but the theologians' task to disprove it. If they don't, their case will go by default, and Scripture must be reinterpreted.
In fact, however, there had never been any question of condemning the Copernican system as a working hypothesis. The biblical objections were only raised against the claim that it was more than a hypothesis, that it was rigorously proven, that it was in fact equivalent to gospel truth. The subtlety in Galileo's manoeuvre is that he does not
explicitly raise this claim. He cannot do so, for he had not produced a single argument in support of it. Now we understand why he needed his black-or-white alternative as a first move: to distract attention from the true status of the Copernican system as an officially tolerated working hypothesis awaiting proof. Instead, by slipping in the ambiguous words "physical proposition" at the beginning of the italicized passage, followed by the demand that "it must be shown to be not rigorously demonstrated", he implied (though he did not dare to state it explicitly) that the truth of the system was rigorously demonstrated. It is all so subtly done that the trick is almost imperceptible to the reader and, as far as I know, has escaped the attention of students to this day. Yet it decided the strategy he was to follow in coming years.
Throughout the document Galileo completely evaded any astronomical or physical discussion of the Copernican system; he simply gave the impression that it was proven beyond doubt. If he had talked to the point, instead of around it, he would have had to admit that Copernicus' forty-odd epicycles and eccentrics were not only not proven but a physical impossibility, a geometrical device and nothing else; that the absence of an annual parallax, i.e. of any apparent shift in the position of the fixed stars, in spite of the new telescopic precision, weighed heavily against Copernicus; that the phases of Venus disproved Ptolemy, but not Herakleides or Tycho; and that all he could claim for the Copernican hypothesis was that it described certain phenomena (the retrogression) more economically than Ptolemy; as against this, the abovementioned physical objections would have carried the day.
For it must be remembered that the system which Galileo advocated was the orthodox Copernican system, designed by the Canon himself, nearly a century before Kepler threw out the epicycles and transformed the abstruse paper-construction into a workable mechanical model. Incapable of acknowledging that any of his contemporaries had a share in the progress of astronomy, Galileo blindly and indeed suicidally ignored Kepler's work to the end, persisting in the futile attempt to bludgeon the world into accepting a Ferris wheel with forty-eight epicycles as "rigorously demonstrated" physical reality.