Galileo Galilei and the Roman Curia/Chapter 2

by Karl von Gebler

CHAPTER II.

THE TELESCOPE AND ITS REVELATIONS.

Term of Professorship at Padua renewed.—Astronomy.—A New Star.— The Telescope.—Galileo not the Inventor.— Visit to Venice to exhibit it.—Telescopic Discoveries.—Jupiter's Moons.—Request of Henry IV.—"Sidereus Nuncius."—The Storm it raised.—Magini's attack on Galileo.—The Ring of Saturn.—An Anagram.—Opposition of the Aristotelian School.—Letter to Kepler.

The first six years of Galileo's professorship at Padua had passed away, but the senate were eager to retain so bright a light for their University, and prolonged the appointment of the professor, whose renown was now great, for another six years, with a considerable increase of salary.^[1]

As we have seen, he had for a long time renounced the prevailing views about the universe; but up to this time he had discussed only physical mathematical questions with the Peripatetic school, the subject of astronomy had not been mooted. But the sudden appearance of a new star in the constellation of Serpentarius, in October, 1604, which, after exhibiting various colours for a year and a half, as suddenly disappeared, induced him openly to attack one of the Aristotelian doctrines hitherto held most sacred, that of the unchangeableness of the heavens. Galileo demonstrated, in three lectures to a numerous audience, that this star was neither a mere meteor, nor yet a heavenly body which had before existed but had only now been observed, but a body which had recently appeared and had again vanished.^[2] The subject, though not immediately connected with the Copernican question, was an important step taken on the dangerous and rarely trodden path of knowledge of nature, uninfluenced by dogmatism or petrified professorial wisdom. This inviolability of the vault of heaven was also conditioned by the prevailing views of the universe. What wonder then that most of the professors who had grown grey in the Aristotelian doctrine (Cremonio for instance, Coressio, Lodovico delle Colombo, and Balthasar Capra) were incensed at these opinions of Galileo, so opposed to all their scientific prepossessions, and vehemently controverted them.

The spark, however, which was to set fire to the abundant inflammable material, and to turn the scientific and religious world, in which doubt had before been glimmering, into a veritable volcano, the spark which kindled Galileo's genius and made him for a long time the centre of that period of storm and stress, was the discovery of the telescope.

We will not claim for Galileo, as many of his biographers have erroneously done, priority in the construction of the telescope. We rely far more on Galileo's own statements than on those of his eulogists, who aim at effect. Galileo relates with perfect simplicity at the beginning of the "Sidereus Nuncius," published at Venice in 1610, that he had heard about ten months ago that an instrument had been made by a Dutchman, by means of which distant objects were brought nearer and could be seen very plainly. The confirmation of the report by one of his former pupils, a French nobleman, Jean Badovere of Paris, had induced him to reflect upon the means by which such an effect could be produced. By the laws of refraction he soon attained his end. With two glasses fixed at the ends of a leaden tube, both having one side flat and the other side of the one being concave and of the other convex, his primitive telescope, which made objects appear three times nearer and nine times larger, was constructed. But now, having "spared neither expense nor labour," he had got so far as to construct an instrument which magnified an object nearly a thousand times, and brought it more than thirty times nearer.^[3] Although, therefore, it is clear from this that the first idea of the telescope does not belong to Galileo, it is equally clear that he found out how to construct it from his own reflection and experiments. Undoubtedly also the merit of having made great improvements in it belongs to him, which is shown by the fact that at that time, and long afterwards, his telescopes were the most sought after, and that he received numerous orders for them from learned men, princes and governments in distant lands, Holland, the birthplace of the telescope, not excepted.^[4] But the idea which first gave to the instrument its scientific importance, the application of it to astronomical observations, belongs not to the original inventor but to the genius of Galileo. This alone would have made his name immortal.^[5]

A few days after he had constructed his instrument, imperfect as it doubtless was, he hastened with it to Venice, having received an invitation, to exhibit it to the doge and senate, for he at once recognised its importance, if not to the full extent. We will now let Galileo speak for himself in a letter which he wrote from Venice to his brother-in-law, Benedetto Landucci:—

"You must know then that about two months ago a report was spread here that in Flanders a spy-glass had been presented to Prince Maurice, so ingeniously constructed that it made the most distant objects appear quite near, so that a man could be seen quite plainly at a distance of two miglia. This result seemed to me so extraordinary that it set me thinking; and as it appeared to me that it depended upon the theory of perspective, I reflected on the manner of constructing it, in which I was at length so entirely successful that I made a spy-glass which far surpasses the report of the Flanders one. As the news had reached Venice that I had made such an instrument, six days ago I was summoned before their highnesses the signoria, and exhibited it to them, to the astonishment of the whole senate. Many noblemen and senators, although of a great age, mounted the steps of the highest church towers at Venice, in order to see sails and shipping that were so far off that it was two hours before they were seen steering full sail into the harbour without my spy-glass, for the effect of my instrument is such that it makes an object fifty miglia off appear as large and near as if it were only five."^[6]

Galileo further relates in the same letter that he had presented one of his instruments to the senate, in return for which his professorship at Padua had been conferred on him for life, with an increase of salary to one thousand florins.^[7]

On his return to Padua he became eagerly engrossed in telescopic observation of the heavens. The astonishing and sublime discoveries which were disclosed to him must in any case have possessed the deepest interest for the philosopher who was continually seeking to solve nature's problems, and were all the more so, since they contributed materially to confirm the Copernican theory.

His observations were first directed to the moon, and he discovered that its surface was mountainous, which showed at all events that the earth's satellite was something like the earth itself, and therefore by no means restored it to the aristocratic position in the universe from which it had been displaced by Copernicus. The milky way, as seen through the telescope, revealed an immense number of small stars. In Orion, instead of the seven heavenly bodies already known, five hundred new stars were seen; the number of the Pleiades, which had been fixed at seven, rose to thirty-six; the planets showed themselves as disks, while the fixed stars appeared as before, as mere bright specks in the firmament.

But the indefatigable observer's far most important discovery, in its bearing on the Copernican theory, was that of the moons of Jupiter, in January 1610. As they exhibited motions precisely similar to those which Copernicus had assumed for the whole solar system, they strongly fortified his theory. It was placed beyond all doubt that our planet was not the centre of all the heavenly bodies, since Jupiter's moons revolved round him. The latter was brought, so to speak, by the discovery of his attendants, into relations with the earth which, considering the prevailing views, were humiliating enough, and the more so since Jupiter had four satellites while the earth had only one. There remained, however, the consoling assurance that he and they revolved round our abode!

In honour of the reigning house of his native country, and as an acknowledgment of favours received from it (for since the accession of Cosmo II.^[8] Galileo had been in high favour), he called Jupiter's moons "Medicean stars." The urgent solicitude of the French court to gain, by Galileo's aid, a permanent place on the chart of the heavens, is very amusing. Thus, on 20th April, 1610, he received a pressing request, "in case he discovered any other fine star, to call it after the great star of France, Henry IV., then reigning, the most brilliant in the whole universe, and to give it his proper name of Henry rather than that of the family name of Bourbon." Galileo communicated this flattering request, as he seems to have considered it, with much satisfaction to the secretary of the Tuscan court, Vincenzo Giugni, in a letter from Padua, on 25th June, 1610,^[9] as an evidence of the great importance attached to his telescopic discoveries. He added that he did not expect to find any more planets, as he had already made many very close observations.

Galileo published by degrees all the discoveries he had made at Padua, of which we have only noticed the most important, in the work before mentioned, the "Sidereus Nuncius"; it was dedicated to the Grand Duke, Cosmo II., and the first edition appeared at Venice, in March, 1610.

Although the unexpected discoveries which Galileo had made with his telescope had confirmed his opinion that the system of Copernicus was the only one consistent with the facts of nature, had indeed made it his absolute conviction, he had not yet ventured to defend it in his works. He contented himself with stating bare facts, without showing their relation to the ideas of Copernicus, leaving this to the learning and insight of the reader. Moreover, the logical inferences from Jupiter's moons must surely stare every thoughtful man in the face, and so indeed they did in a way very unwelcome to the scientific conservatives.

The storm raised by Galileo's latest announcements was tremendous. People heard with amazement the extraordinary things which the new invention had brought to light, and paid a just tribute of admiration to the man to whose labours it was due. But these discoveries were so directly opposed to the traditional natural philosophy, still regarded as the highest wisdom, that the "Sidereus Nuncius" had met with many opponents. It must however be borne in mind that at the time of its first publication very few of the learned were in a position to convince themselves with their own eyes of the correctness of the appearances seen with the telescope, simply because they had not the instrument at hand. From this cause, even Kepler did not see the satellites of Jupiter till 30th August, 1610. But men so free from jealousy and prejudice as Kepler (who, on reading the "Sidereus Nuncius," at once recognised the truth of the discoveries, and said with enthusiasm that "Galileo had in this book given evidence of the divinity of his genius"^[10]), have at all times been rare.

At first, therefore, the majority of the learned world shook their heads incredulously about the phenomena announced by the "Nuncius," especially in Italy, where envy lent its aid to bring an armed opposition into the field. Little did it at first avail that Kepler, renowned as the first astronomer in Germany, was on the side of the "Sidereus Nuncius"; for in May of the same year he had a reprint of the work issued at Prague, with an introduction in which he expressed his entire conviction of the truth of the telescopic discoveries made known by it, and answered all objections.^[11] In vain. These new discoveries were too revolutionary to be believed. Even upright and estimable scientific men, like Welser in Augsburg, and Clavius at Rome, did not give credit to Galileo's statements until they learnt better by their own observations. The latter, who was the first mathematician in Rome in his day, even said "he laughed at the pretended satellites of Jupiter; you must construct a telescope which would first make them and then show them." Let Galileo hold his own opinions, and he (Clavius) would hold his.^[12]

But the leader of an unworthy agitation in Italy against Galileo was a man who assumed this attitude from very different motives from the sacred service of science. This was the well-known Professor Magini, astronomer at the university of Bologna, who, next to Galileo, enjoyed the highest reputation for learning in Italy. He could not brook that his famous countryman should all at once obtain the highest fame with seven-league boots, leaving a pigmy like himself far behind, by means of the discoveries made known in his "Sidereus Nuncius." He must not only be refuted, the refutation must be circulated as widely as possible. But the most repulsive feature in Magini's conduct towards Galileo is his double-facedness. He never openly ventured with any work into the arena himself, but incited others all the more from behind concealment.^[13] Even if we do not, with Martin Hasdal and Alexander Sertini, accuse him of being exactly the instigator of the famous libel "Peregrinatio contra Nuncium Sidereum," published by his assistant, Martin Horky, against Galileo in 1610, which excited the indignation of all the right-minded learned world, we cannot acquit him of complicity with him, and of having had a hand, more or less, in that pamphlet. The suspicion is strongly confirmed by the ostentation with which Magini, when told of the publication of the "Peregrinatio," drove the author, with disgust and ridicule, out of his house, and took occasion to assert on all hands that he had nothing whatever to do with the shameful act of his famulus, an assertion in strange contradiction with the excuse afterwards made by Horky to Kepler.^[14] By Kepler's advice Galileo did not do him the honour of answering. The task was undertaken by Wedderburn, a Scotchman, formerly a pupil of Galileo's, and Antonio Roffeni, professor of philosophy at the university of Bologna; the former at Padua during the same year, the latter at Bologna in 1611.^[15]

Meanwhile, in July, 1610, Galileo had observed a new appearance in the heavens by means of his telescope, the ring of Saturn. In consequence, however, of the imperfection of the instrument, it did not appear like a ring, but Saturn looked like a triple star. Galileo, who on the one hand did not wish to make the new discovery public until he had sufficiently observed it, yet feared on the other that some one might claim priority, at once communicated it in a letter from Padua, 30th July, 1610,^[16] to his influential friend Belisario Vinta, chief secretary of state to Cosmo II., but urgently begged him to keep it a secret. But even this did not seem sufficient to secure his right to the first observation of Saturn, so he announced it to his friends in the following absurd anagram:—

SMAJSMRMJLMEPOETALEVNJPVNENVGTTAVJRAS.

Kepler puzzled for a long time over this enigma, and at last only made out the barbaric line, "Salve umbistineum geminatum Martia proles," which he incorrectly applied to the planet Mars. At length, after repeated requests, and after Julian de' Medici, Tuscan ambassador at the Imperial court, had been charged by the Emperor to ask for a solution, he complied with the illustrious wish, and in a letter to Julian of 13th November, 1610,^[17] gave the following startling explanation:—

Altissimum Planetam tergeminum observavi.

The learned and semi-learned world of Italy had not yet had time to become reconciled to the surprising discoveries announced in the "Sidereus Nuncius" of March in the same year, when the asserted triple nature of Saturn contravened the prevailing idea that there was nothing new to be discovered in the heavens. The recognition of Galileo's telescopic discoveries made way very slowly. From the first he spared no pains in popularising them. He did this repeatedly in public lectures, and with so much success that he could write to Vinta: "even the most exalted personages, who have been most vehement in attacking my doctrines, at length gave up the game for lost, and acknowledged, coram populo, that they were not only convinced but ready to defend them against those philosophers and mathematicians who ventured to attack them."^[18]

But it was only at the University of Padua that Galileo could report such rapid progress; and until the Maginis, Clavios, and others were convinced by their own eyes, and confirmed to their own party the truth of Galileo's disclosures, he had to sustain a hard struggle with incredulity, malice, and peripatetic fanaticism. Some rabid Aristotelians went so far as to say that Galileo's telescope was so constructed as to show things that did not exist! Nor did it mend the matter much when he offered 10,000 scudi to any one who should construct so cunning an instrument.^[19] Others resolutely refused even to look through the telescope, giving it as their firm conviction that they would not be able to see appearances which Aristotle had not said a word about in all his books! The answer that Aristotle was not acquainted with the telescope, and could not have known anything of telescopic appearances, rebounded without effect from the petrified infallibility of Aristotelian wisdom. Nor must it be supposed that these short-sighted conservatives only numbered a few would-be savans of the Peripatetic school; on the contrary, celebrities like Cesare Cremonino da Cento, and Julius Libri, denied Galileo's discoveries a priori.^[20] When Libri died in December, 1610, without having been willing to look through a telescope, and protesting against Galileo's "absurdities," Galileo wrote in a letter of 17th December that this rigid opponent of his "absurdities," as he was never willing to look at them from earth, might perhaps see them on his way to heaven!^[21]

Some passages from a letter of Galileo's to Kepler, of 19th August, 1610, will best show how some of these men of science turned away with a righteous awe from the inconvenient recognition of the truth. Galileo writes among other things:—

"You are the first and almost the only person who, even after but a cursory investigation, has, such is your openness of mind and lofty genius, given entire credit to my statements. . . . We will not trouble ourselves about the abuse of the multitude, for against Jupiter even giants, to say nothing of pigmies, fight in vain. Let Jupiter stand in the heavens, and let the sycophants bark at him as they will. . . . In Pisa, Florence, Bologna, Venice, and Padua many have seen the planets; but all are silent on the subject and undecided, for the greater number recognise neither Jupiter nor Mars and scarcely the moon as planets. At Venice one man spoke against me, boasting that he knew for certain that my satellites of Jupiter, which he had several times observed, were not planets because they were always to be seen with Jupiter, and either all or some of them, now followed and now preceded him. What is to be done? Shall we side with Democritus or Heraclitus? I think, my Kepler, we will laugh at the extraordinary stupidity of the multitude. What do you say to the leading philosophers of the faculty here, to whom I have offered a thousand times of my own accord to show my studies, but who with the lazy obstinacy of a serpent who has eaten his fill have never consented to look at planets, nor moon, nor telescope? Verily, just as serpents close their ears, so do these men close their eyes to the light of truth. These are great matters; yet they do not occasion me any surprise. People of this sort think that philosophy is a kind of book like the Æneid or the Odyssey, and that the truth is to be sought, not in the universe, not in nature, but (I use their own words) by comparing texts! How you would laugh if you heard what things the first philosopher of the faculty at Pisa brought against me in the presence of the Grand Duke, for he tried, now with logical arguments, now with magical adjurations, to tear down and argue the new planets out of heaven."^[22]

1. Op. xv. p. 390. His salary at first was 72 Florentine zecchini=£18, and rose by degrees to 400 zecchini=£100. (Op. viii. p. 18, note 3.)
2. Some fragments of these lectures are extant, and are included by Albèri in the Op. v. part ii.
3. Op. iii. ("Astronomicus Nuncius," pp. 60,61.) In his "Saggiatore" also he relates the circumstance in precisely the same way, only adding that he devised the construction of the telescope in one night, and carried it out the next day.
4. Nelli, pp. 186, 187.
5. History has acknowledged the optician Hans Lipperhey, of Middelburg, to be the inventor of the telescope. Compare the historical sketch in "Das neue Buch der Erfindungen," etc., vol. ii. pp. 217-220. (Leipzig, 1865.) The instrument received its name from Prince Cesi, who, on the advice of the learned Greek scholar Demiscianus, called it a "teleskopium."
6. Op. vi. pp. 75-77.
7. See the decree of the senate, 25th Aug., 1609. (Op. xv. pp. 392, 393 )
8. Cosmo II. showed all his life a sincere attachment to his old teacher, Galileo. From 1605, before Cosmo was reigning prince, Galileo had regularly given him mathematical lessons during the academical holidays at Florence, and had thereby gained great favour at the court of Tuscany.
9. Op. vi. pp. 107-111.
10. See the letter of Martin Hasdal from Prague, of 15th April, 1610, to Galileo (Op. viii. pp. 58-60); also a letter from Julian de' Medici, Tuscan ambassador at the Imperial court, to Galileo, from Prague, 19th April, 1610. (Wolynski, "Lettere inedite," etc., p. 20.)
11. This reprint bore the following superscription: "Joannis Kepleri Mathematici Cæsarei Dissertatio cum Nuncio Sidereo nuper ad mortales misso a Galilaeo Galilaeo Mathematico Patavino." Comp. Venturi, vol. i. pp. 99-120.
12. Op. vi. p. 121, note 1.
13. Compare the letters of Martin Hasdal, Alexander Sertini, and Kepler to Galileo in 1610. (Op. viii. pp. 60-63, 65-68, 82-85, 88, 89, 101, 113-117.)
14. See the letter which Kepler wrote about it to Galileo on 25th Oct. 1610. (Op. viii. pp. 113-117.)
15. Wedderburn's reply was called: "Quatuor Problematum, quæ Martinius Horky contra Nuncium Sidereum de quatuor Planetis novis proposuit"; Roffeni's, "Epistola apologetica contra cœcam peregrinationem cujusdam furiosi Martini cognomine Horky editam adversus, Nuncium Sidereum."
16. Op. vi. pp. 114, 115.
17. Op. vi. p. 127.
18. May 7th, 1610. (Op. vi. pp. 93-99.)
19. Op. vi. p. 165.
20. Op. xv. (Viviani), p. 343.
21. Op. vi. p. 129.
22. Op. vi. pp. 116-118. Ponsard in his drama, "Galileo," of which a third edition appeared at Paris in 1873, in which he mostly turns history upside down, in Act i. sc. iii, and iv. takes off capitally the proud and silly opposition of the Aristotelians.