Treatise on Floating Bodies.—Controversy with Scheiner about the Solar Spots.—Favourable reception of Galileo’s work on the subject at Rome.—Discussion with the Grand Duchess Christine.—The Bible brought into the controversy.—Ill-fated Letter to Castelli.—Caccini’s Sermon against Galileo.—Lorini denounces the Letter to the Holy Office.—Archbishop Bonciani’s attempts to get the original Letter.—“Opinion” of the Inquisition on it.—Caccini summoned to give evidence.—Absurd accusations.—Testimony of Ximenes and Attavanti in Galileo’s favour. While the storm which was to burst over Galileo’s head was thus slowly gathering, he was making important progress in the departments of physics and mechanics.
His treatise on the motion of floating bodies led to very important results.[82] In it he again took the field against the Peripatetic philosophers, and refuted the assertion of Aristotle that the floating or partial immersion of bodies in water depended chiefly on their form, for by his approved method of studying the open book of nature he clearly showed the error of that opinion. In this work Galileo laid the foundations of hydrostatics as mostly held to this day. The old school rose up once more to refute him, as a matter of course; but their polemics cut a pitiful figure, for the champions of antiquated wisdom had in their impotence mostly to content themselves with wretched sophisms as opposed to Galileo’s hard facts, and as a last resort to insist on the authority of Aristotle.
The combatants who took the field with various writings to[43] defend the Peripatetic school against these fresh attacks of Galileo were the professors Giorgio Corressio, Tommaso Palmerini, Lodovico delle Colombo, in 1612, and in 1613 Vincenzo di Grazia. Corressio was answered by Benedetto Castelli; but the work, which is preserved in MS. in the National Library at Florence, was not published, out of pity for his opponent who, in the meantime, had been overtaken by severe misfortune. Although professing to be a Roman Catholic, he was discovered to belong to the Greek Non-Uniat church, which entailed the loss of his professorship at the University of Pisa. Galileo intended himself to answer Palmerini, but while he was doing so Palmerini died, and not wishing to fight a dead man, he laid his reply aside. The lame objections of the other two received a brilliant refutation in a work published in 1615 by Castelli. From the original MS., however, in the National Library at Florence, which is mostly in Galileo’s handwriting, it is evident that he was the real author.[83]
During the same year in which he had so alarmed the Peripatetics by the treatise on floating bodies, he was much occupied with the controversy with the Jesuit father, Scheiner, before mentioned, professor of mathematics at Ingolstadt, about the solar spots and the priority of their discovery. In three letters to Welser of Augsburg (published there in 1612) he had claimed for himself, under the pseudonym of “Apelles,” the earliest observation of these appearances, and explained them conformably to the traditional opinions. He propounded the ingenious idea that these spots were a multitude of little planets, passing over the sun’s disk as they revolved round the earth. By this clever explanation he secured the applause of all the Peripatetic school, and proclaimed himself the decided foe of Galileo. Challenged to do so by Welser, Galileo replied in three letters addressed to him, in which “Apelles” came off but poorly.[84] Galileo convincingly[44] refuted his opponent’s explanation of the spots, and brilliantly defended his own right to the priority of their discovery by appealing to witnesses to whom he had made it known in 1610. These letters, together with Scheiner’s, were published in March, 1613, under the title “History and Explanation of the Solar Spots,”[85] with a fine portrait of Galileo, and a dedication to his illustrious friend Salviati, of the “Accadémia dei Lincei.”
The publication of this work was of especial significance, because it was the first in which Galileo decidedly takes the side of the Copernican system. This accounts for the extraordinary sensation made by these essays. The controversy on the two systems came more and more to the front. And yet, notwithstanding all this, no theological scruples seem at first to have been felt at Rome, even in the highest ecclesiastical circles. On the contrary, we find the cardinals Maffeo Barberini[86] (afterwards Pope Urban VIII.), and Federigo Borromeo,[87] thanking Galileo in the most friendly terms for sending them his work, and expressing their sincere admiration for the researches described in it. And Battista Agucchia, then one of the first officials at the court of Rome, and afterwards secretary of Pope Gregory XV., in a similar letter of thanks,[88] not only fully endorsed these opinions, but expressed his firm belief that they would in time be universally acknowledged, although now they had many opponents, partly from their novelty and remarkable character, and partly from the envy and obstinacy of those who had from the first maintained the contrary view.
The scientific circles of the university town of Pisa were far less friendly to the Copernican ideas than the higher ecclesiastics at the papal residence. Father Castelli, who in[45] October of the same year was called to the chair of mathematics at this university, reports in a letter of 6th November,[89] in which he tells Galileo what reception he had met with from the heads of the college, that the proveditor of the university, Mgr. d’Elci, had expressly forbidden him at his first interview to treat in his lectures of the double motion of the earth, or even to take occasion in any digression to mention it as probable!
An accidental circumstance, however, was the immediate cause of turning the controversy into the channel which proved so fatal to Galileo. One day in December, 1613, Castelli and several other learned men were guests at the Grand Duke’s table at Pisa, where the court was then staying. The conversation turned chiefly on the remarkable phenomena of the Medicean stars, whose veritable existence in the heavens Boscaglia, professor of physics at the university, was constrained with a heavy heart to confirm, in answer to a question of the Grand Duke’s mother, Christine. Castelli eagerly seized the opportunity of applauding Galileo’s splendid discovery. Boscaglia, a Peripatetic of the purest water, could not master his displeasure, and whispered meanwhile to the Grand Ducal mother that all Galileo’s telescopic discoveries were in accord with the truth, only the double motion of the earth seemed incredible, nay impossible, as the Holy Scriptures were clearly opposed to it. The repast was then over, and Castelli took leave; but he had scarcely left the palace when he saw Christine’s porter hastening after him and calling him back. He obeyed, and found the whole company still assembled in the Grand Duke’s apartments. Christine now began, after a few introductory remarks, to attack the Copernican doctrines, appealing to Holy Scripture. Castelli at first made some humble attempts to avoid bringing the Bible into the controversy; but as this was of no avail he resolutely took the theological standpoint, and defended the modern views of the universe so impressively and convincingly[46] that nearly all present, even the Grand Duke and his consort, took his side, and the Duchess dowager alone made any opposition. Boscaglia, however, who had been the cause of the unedifying scene, took no part whatever in the discussion.
Castelli hastened to apprise Galileo of this incident, but remarked expressly in his striking letter that it appeared to him that the Grand Duchess Christine had merely persisted in opposition, in order to hear his replies.[90]
This then was the provocation to that famous letter of Galileo’s to his friend and pupil Castelli, in which for the first time theological digressions occur, and which therefore, although by no means intended for publication, was to be eagerly turned to account by his opponents, and to form the groundwork of the subsequent trial. From what has been related it will be seen that the reproach often brought against Galileo that it was he who first introduced the theological question into the scientific controversy about the two systems is entirely unwarranted. On the contrary, these explanations to Castelli, of 21st December, bear telling testimony to the indignation which Galileo felt in seeing the Scriptures involved in a purely scientific discussion, and that the right of deciding the question should even be accorded to them. He sharply defines the relation in which the Bible stands to natural science, marking the limits which it can only pass at the expense of the healthy understanding of mankind. As a good Catholic he fully admits that the Scriptures cannot lie or err, but thinks that this does not hold good of all their expositors. They will involve themselves in sad contradictions, nay, even in heresies and blasphemy, if they always interpret the Bible in an absolutely literal sense. Thus, for instance, they must attribute to God hands, feet, and ears, human feelings such as anger, repentance, hatred, and make Him capable of forgetfulness and ignorance of the future.
“As therefore,” continues Galileo, “the Holy Scriptures in[47] many places not only admit but actually require a different explanation from what seems to be the literal one, it seems to me that they ought to be reserved for the last place in mathematical discussions. For they, like nature, owe their origin to the Divine Word; the former as inspired by the Holy Spirit, the latter as the fulfilment of the Divine commands; it was necessary, however, in Holy Scripture, in order to accommodate itself to the understanding of the majority, to say many things which apparently differ from the precise meaning. Nature, on the contrary, is inexorable and unchangeable, and cares not whether her hidden causes and modes of working are intelligible to the human understanding or not, and never deviates on that account from her prescribed laws. It appears to me therefore that no effect of nature, which experience places before our eyes, or is the necessary conclusion derived from evidence, should be rendered doubtful by passages of Scripture which contain thousands of words admitting of various interpretations, for every sentence of Scripture is not bound by such rigid laws as is every effect of nature.”
Galileo goes on to ask: if the Bible, in order to make itself intelligible to uneducated persons, has not refrained from placing even its main doctrines in a distorted light, by attributing qualities to God which are unlike His character and even opposed to it, who will maintain that in speaking incidentally of the earth or the sun it professes to clothe its real meaning in words literally true? Proceeding on the principle that the Bible and nature are both irrefragable truths, Galileo goes on to draw the following conclusions.
“Since two truths can obviously never contradict each other, it is the part of wise interpreters of Holy Scripture to take the pains to find out the real meaning of its statements, in accordance with the conclusions regarding nature which are quite certain, either from the clear evidence of sense or from necessary demonstration. As therefore the Bible, although dictated by the Holy Spirit, admits, from the reasons given above, in many passages of an interpretation other than the[48] literal one; and as, moreover, we cannot maintain with certainty that all interpreters are inspired by God, I think it would be the part of wisdom not to allow any one to apply passages of Scripture in such a way as to force them to support, as true, conclusions concerning nature the contrary of which may afterwards be revealed by the evidence of our senses or by necessary demonstration. Who will set bounds to man’s understanding? Who can assure us that everything that can be known in the world is known already? It would therefore perhaps be best not to add, without necessity, to the articles of faith which refer to salvation and the defence of holy religion, and which are so strong that they are in no danger of having at any time cogent reasons brought against them, especially when the desire to add to them proceeds from persons who, although quite enlightened when they speak under Divine guidance, are obviously destitute of those faculties which are needed, I will not say for the refutation, but even for the understanding of the demonstrations by which the higher sciences enforce their conclusions.
I am inclined to think that the authority of Holy Scripture is intended to convince men of those truths which are necessary for their salvation, and which being far above man’s understanding cannot be made credible by any learning, or any other means than revelation by the Holy Spirit. But that the same God who has endowed us with senses, reason, and understanding, does not permit us to use them, and desires to acquaint us in any other way with such knowledge as we are in a position to acquire for ourselves by means of those faculties, that it seems to me I am not bound to believe, especially concerning those sciences about which the Holy Scriptures contain only small fragments and varying conclusions; and this is precisely the case with astronomy, of which there is so little that the planets are not even all enumerated.”
Having emphatically declared that thus dragging the Bible into a scientific controversy was only a subterfuge of his[49] opponents, who, feeling that they could not successfully fight him on his own ground, had entrenched themselves behind an unassailable bulwark, Galileo proceeds to discuss the well known passage in Joshua which the Aristotelians were fond of adducing to demonstrate the contradictions between the modern views and Holy Scripture. His object is to beat his adversaries with their own weapons, by showing that if this passage is taken literally, and God really arrested the sun in his course in answer to Joshua’s prayer, and thus prolonged the day, it makes the incorrectness, nay the impossibility, of the Ptolemaic system quite clear, while the Copernican agrees with it very well. According to the Ptolemaic ideas, Galileo goes on, the sun has two motions, the annual one from west to east, and the daily one from east to west. Being diametrically opposed to each other, they cannot both be the sun’s own motions. The annual motion is the one which belongs to it; the other originates in the primum mobile, which carries the sun round the earth in twenty-four hours and occasions day and night. If therefore God desired to prolong the day (supposing the Ptolemaic system to be the right one) He must have commanded, not the sun but the primum mobile, to stand still. Now, as it is stated in the Bible that God arrested the sun in its course, either the motions of the heavenly bodies must be different from what Ptolemy maintained them to be, or the literal meaning must be departed from, and we must conclude that the Holy Scriptures, in stating that God commanded the sun to stand still, meant the primum mobile, but, accommodating themselves to the comprehension of those who are scarcely able to understand the rising and setting of the sun, said just the opposite of what they would have said to scientifically educated people. Galileo also says that it was highly improbable that God should have commanded the sun alone to stand still, and have allowed the other stars to pursue their course, as all nature would have been deranged by it without any occasion, and his belief was that God had enjoined a temporary rest on the[50] whole system of the universe, at the expiration of which all the heavenly bodies, undisturbed in their mutual relations, could have begun to revolve again in perfect order: doubtless his inmost conviction, although to us it sounds like irony.
At the close of this long letter he explains how the literal sense of the passage accords with the Copernican system. By his discovery of the solar spots the revolution of the sun on its axis is demonstrated; moreover it is also ver............