COPERNICUS accomplished much, but even his genius could not far outrun the times in which he lived. When one realizes that not only all the astronomers before him, but he and his immediate successor, Tycho Brahe, made all their observations and calculations unaided by even the simplest telescope, by logarithms or by pendulum clocks for accurate measurement of time,[140] one marvels not at their errors, but at the greatness of their genius in rising above such difficulties. This lack of material aids makes the work of Tycho Brahe,[141] accounted one of the greatest observers that has ever lived,[142] as notable in its way perhaps as that of Copernicus.
His life[143] was a somewhat romantic one. Born of noble family on December 14th, 1546, at Knudstrup in Denmark, Tyge Brahe, the second of ten children,[144] was early practically adopted by his father's brother. His family wished him to become a statesman and sent him in 1559 to the university at Copenhagen to prepare for that career. A partial eclipse of the sun on August 21st, 1560 as foretold by the astronomers thrilled the lad and determined him to study a science that could foretell the future and so affect men's lives.[145] When he was sent to Leipsic with a tutor in 1562 to study law, he devoted his time and money to the study of mathematics and astronomy. Two years later when eighteen years of age, he resolved to perform anew the task of Hipparchos and Ptolemy and make a catalogue of the stars more accurate than theirs. His family hotly opposed these plans; and for six years he wandered through the German states, now at Wittenberg, now at Rostock (where he fought the duel in which he lost part of his nose and had to have it replaced by one of gold and silver)[146] or at Augsburg—everywhere working on his chosen subjects. But upon his return to Denmark (1570) he spent two years on chemistry and medicine, till the startling appearance of the New Star in the constellation of Cassiopæa (November, 1572) recalled him to what became his life work.[147]
Through the interest and favor of King Frederick II, he was given the island of Hveen near Elsinore, with money to build an observatory and the pledge of an annual income from the state treasury for his support.[148] There at Uraniborg from 1576 to 1597 he and his pupils made the great catalogue of the stars, and studied comets and the moon. When he was forced to leave Hveen by the hostility and the economical tendencies of the young king,[149] after two years of wandering he accepted the invitation of the Emperor Rudolphus and established himself at Prague in Bohemia. Among his assistants at Prague was young Johann Kepler who till Tycho's death (on October 24, 1601) was his chief helper for twenty months, and who afterwards completed his observations, publishing the results in the Rudolphine Tables of 1627.
This "Phoenix among Astronomers"—as Kepler calls him,[150]—was the father of modern practical astronomy.[151] He also propounded a third system of the universe, a compromise between the Ptolemaic and the Copernican. In this the Tychonic system,[152] the earth is motionless and is the center of the orbits of the sun, the moon, and the sphere of the fixed stars, while the sun is the center of the orbits of the five planets.[153] Mercury and Venus move in orbits with radii shorter than the sun's radius, and the other three planets include the earth within their circuits. This system was in harmony with the Bible and accounted as satisfactorily by geometry as either of the other two systems for the observed phenomena.[154] To Tycho Brahe, the Ptolemaic system was too complex,[155] and the Copernican absurd, the latter because to account for the absence of stellar parallax it left vacant and purposeless a vast space between Saturn and the sphere of the fixed stars,[156] and because Tycho's observations did not show any trace of the stellar parallax that must exist if the earth moves.[157]
Though Tycho thus rejected the Copernican theory, his own proved to be the stepping stone toward the one he rejected,[158] for by it and by his study of comets he completely destroyed the ideas of solid crystalline spheres to the discredit of the scholastics; and his promulgation of a third theory of the universe helped to diminish men's confidence in authority and to stimulate independent thinking.
Copernicus worked out his system by mathematics with but slight aid from his own observations. It was a theory not yet proven true. Tycho Brahe, though denying its validity, contributed in his mass of painstaking, accurate observations the raw material of facts to be worked up by Kepler into the great laws of the planets attesting the fundamental truth of the Copernican hypothesis.
Johann Kepler[159] earned for himself the proud title of "lawmaker for the universe" in defiance of his handicaps of ill-health, family troubles, and straitened finances.[160] Born in Weil, Wurtemberg, (December 27, 1571) of noble but indigent parents, he was a sickly child unable for years to attend school regularly. He finally left the monastery school in Mulifontane in 1586 and entered the university at Tübingen to stay for four and a half years. There he studied philosophy, mathematics, and theology (he was a Lutheran) receiving the degree of Master of Arts in 1591. While at the university he studied under Mæstlin, professor of mathematics and astronomy, and a believer in the Copernican theory. Because of Mæstlin's teaching Kepler developed into a confirmed and enthusiastic adherent to the new doctrine.
In 1594 he reluctantly abandoned his favorite study, philosophy, and accepted a professorship in mathematics at Grætz in Styria. Two years later he published his first work: Prodromus Dissertationum continens mysterium cosmographicum etc. (1596) in which he sought to prove that the Creator in arranging the universe had thought of the five regular bodies which can be inscribed in a sphere according to which He had regulated the order, the number and the proportions of the heavens and their movements.[161] The book is important not only because of its novelty, but because it gave the Copernican doctrine public explanation and defense.[162] Kepler himself valued it enough to reprint it with his Harmonia Mundi twenty-five years later. And it won for him appreciative letters from various scientists, notably from Tycho Brahe and Galileo.[163]
As Kepler, a Lutheran, was having difficulties in Grætz, a Catholic city, he finally accepted Tycho's urgent invitation to come to Prague.[164] He came early in 1600, and after some adjustments had been made between the two,[165] he and his family settled with Tycho that autumn to remain till the latter's death the following November. Kepler himself then held the office of imperial mathematician by appointment for many years thereafter.[166]
With the researches of Tycho's lifetime placed at his disposal, Kepler worked out two of his three great planetary laws from Tycho's observations of the planet Mars. Yet, as M. Bertrand remarks,[167] it was well for Kepler that his material was not too accurate or its variations (due to the then unmeasured force of attraction) might have hindered him from proving his laws; and luckily for him the earth's orbit is so nearly circular that in calculating the orbit of Mars to prove its elliptical form, he could base his work on the earth's orbit as a circle without vitiating his results for Mars.[168] That a planet's orbit is an ellipse and not the perfect circle was of course a triumph for the new science over the scholastics and Aristotelians. But they had yet to learn what held the planets in their courses.
From Kepler's student days under Mæstlin when as the subject of his disputation he upheld the Copernican theory, to his death in 1630, he was a staunch supporter of the new teaching.[169] In his Epitome Astronomiæ Copernicanæ (1616) he answered objections to it at length.[170] He took infinite pains to convert his friends to the new system. It was in vain that Tycho on his deathbed had urged Kepler to carry on their work not on the Copernican but on the Tychonic scheme.[171]
Kepler had reasoned out according to physics the laws by which the planets moved.[172] In Italy at this same time Galileo with his optic tube (invented 1609) was demonstrating that Venus had phases even as Copernicus had declared, that Jupiter had satellites, and that the moon was scarred and roughened—ocular proof that the old system with its heavenly perfection in number (7 planets) and in appearance must be cast aside. Within a year after Galileo's death Newton was born[173] (January 4, 1643). His demonstration of the universal application of the law of gravitation (1687) was perhaps the climax in the development of the Copernican system. Complete and final proof was adding in the succeeding years by Roemer's (1644-1710) discovery of the velocity of light, by Bradley's (1693-1762) study of its aberration,[174] by Bessel's discovery of stellar parallax in 1838,[175] and by Foucault's experimental demonstration of the earth's axial motion with a pendulum in 1851.[176]
DURING the lifetime of Copernicus, Roman Catholic churchmen had been interested in his work: Cardinal Schönberg wrote for full information, Widmanstadt reported on it to Pope Clement VII and Copernicus had dedicated his book to Pope Paul III.[177] But after his death, the Church authorities apparently paid little heed to his theory until some fifty years later when Giordano Bruno forced it upon their attention in his philosophical teachings. Osiander's preface had probably blinded their eyes to its implications.
The Protestant leaders were not quite so urbane in their attitude. While Copernicus was still alive, Luther is reported[178] to have referred to this "new astrologer" who sought to prove that the earth and not the firmament swung around, saying: "The fool will overturn the whole science of astronomy. But as the Holy Scriptures state, Joshua bade the sun stand still and not the earth." Melancthon was more interested in this new idea, perhaps because of the influence of Rheticus, his colleague in the University of Wittenberg and Copernicus's great friend and supporter; but he too preferred not to dissent from the accepted opinion of the ages.[179] Informally in a letter to a friend he implies the absurdity of the new teaching,[180] and in his Initia Doctrinæ Physicæ he goes to some pains to disprove the new assumption not merely by mathematics but by the Bible, though with a kind of apology to other physicists for quoting the Divine Witness.[181] He refers to the phrase in Psalm XIX likening the sun in its course "to a strong man about to run a race," proving that the sun moves. Another Psalm states that the earth was founded not to be moved for eternity, and a similar phrase occurs in the first chapter of Ecclesiastes. Then there was the miracle when Joshua bade the sun stand still. While this is a sufficient witness to the truths there are other proofs: First, in the turning of a circumference, the center remains motionless. Next, changes in the length of the day and of the seasons would ensue, were the position of the earth in the universe not central, and it would not be equidistant from the two poles. (He has previously disposed of infinity by stating that the heavens revolve around the pole, which could not happen if a line drawn from the center of the universe were infinitely projected).[182] Furthermore, the earth must be at the center for its shadow to fall upon the moon in an eclipse. He refers next to the Aristotelian statement that to a simple body belongs one motion: the earth is a simple body; therefore it can have but one motion. What is true of the parts applies to the whole; all the parts of the earth are borne toward the earth and there rest; therefore the whole earth is at rest. Quiet is essential to growth. Lastly, if the earth moved as fast as it must if it moves at all, everything would fly to pieces.[183]
Melancthon thus sums up the usual arguments from the Scriptures, from Aristotle, Ptolemy and the then current physics, in opposition to this theory. Not only did he publish his own textbook on physics, but he republished Sacrobosco's famous introduction to astronomy, writing for it a preface urging diligent study of this little text endorsed by so many generations of scholars.
Calvin, the great teacher of the Protestant Revolt, apparently was little touched by this new intellectual current.[184] He did write a semi-popular tract[185] against the so called "judicial" astrology, then widely accepted, which he, like Luther, condemns as a foolish superstition, though he values "la vraie science d'astrologie" from which men understand not merely the order and place of the stars and planets, but the causes of things. In his Commentaries, he accepts the miracle of the sun's standing still at Joshua's command as proof of the faith Christ commended, so strong that it will remove mountains; and he makes reference only to the time-honored Ptolemaic theory in his discussion of Psalm XIX.[186]
For the absolute authority of the Pope the Protestant leaders substituted the absolute authority of the Bible. It is not strange, then, that they ignored or derided a theory as yet unsupported by proof and so difficult to harmonize with a literally accepted Bible.
How widespread among the people generally did this theory become in the years immediately following the publication of the De Revolutionibus? M. Flammarion, in his Vie de Copernic (1872), refers[187] to the famous clock in the Strasburg Cathedral as having been constructed by the University of Strasburg in protest against the action taken by the Holy Office against Galileo, (though the clock was constructed in 1571 and Galileo was not condemned until 1633). This astronomical clock constructed only thirty years after the death of Copernicus, he claims represented the Copernican system of the universe with the planets revolving around the sun, and explained clearly in the sight of the people what was the thought of the makers. Lest no one should miscomprehend, he adds, the portrait of Copernicus was placed there with this inscription: Nicolai Copernici vera effigies, ex ipsius autographo depicta.
This would be important evidence of the spread of the theory were it true. But M. Flammarion must have failed to see a brief description of the Strasburg Clock written in 1856 by Charles Schwilgué, son of the man who renovated its mechanism in 1838-1842. He describes the clock as it was before his father made it over and as it is today. Originally constructed in 1352, it was replaced in 1571 by an astrolabe based on the Ptolemaic system; six hands with the zodiacal signs of the planets gave their daily movements and, together with a seventh representing the sun, revolved around a map of the world.[188] When M. Schwilgué repaired the clock in 1838, he changed it to harmonize with the Copernican system.[189]
But within eighteen years after the publication of the De Revolutionibus, proof of its influence is to be found in such widely separated places as London and the great Spanish University of Salamanca. In 1551, Robert Recorde, court physician to Edward and to Mary and teacher of mathematics, published in London his Castle of Knowledge, an introduction to astronomy and the first book printed in England describing the Copernican system.[190] He evidently did not consider the times quite ripe for a full avowal of his own allegiance to the new doctrine, but the remarks of the Maister and the Scholler are worth repeating:[191]
"Maister: ... howbeit Copernicus a man of great learning, of much experience, and of wonderfull diligence in observation, hath renewed the opinion of Aristarchus Samius, affirming that the earth, not onely moveth circularly about his owne centre, but also may be, yea and is, continually out of the precise centre of the world eight and thirty hundred thousand miles: but because the understanding of that controversie depends of profounder knowledge than in this Introduction may be uttered conveniently, I wil let it passe til some other time.
"Scholler: Nay sit, in good faith, I desire not to heare such vaine fantasies, so farre against the common reason, and repugnant to the content of all the learned multitude of Writers, and therefore let it passe for ever and a day longer.
"Maister: You are too yong to be a good judge in so great a matter: it passeth farre your learning, and their's also, that are much better learned than you, to improuve his supposition by good arguments, and therefore you were best condemne nothing that you do not well understand: but an other time, as I saide, I will so declare his supposition, that you shall not onely wonder to heare it, but also peradventure be as earnest then to credite it, as you are now to condemne it: in the meane season let us proceed forward in our former order...."
This little book, reprinted in 1556 and in 1596, and one of the most popular of the mathematical writings in England during that century, must have interested the English in the new doctrine even before Bruno's emphatic presentation of it to them in the eighties.
Yet the English did not welcome it cordially. One of the most popular books of this period was Sylvester's translation (1591) of DuBartas's The Divine Weeks which appeared in France in 1578, a book loved especially by Milton.[192] DuBartas writes:[193]
|
"Those clerks that think—think how absurd a jest! That neither heavens nor stars do turn at all, Nor dance around this great, round earthly ball, But the earth itself, this massy globe of our's, Turns round about once every twice twelve hours! And we resemble land-bred novices New brought aboard to venture on the seas; Who at first launching from the shore suppose The ship stands still and that the firm earth goes." |
Quite otherwise was the situation in the sixteenth century at the University of Salamanca. A new set of regulations for the University, drawn up at the King's order by Bishop Covarrubias, was published in 1561. It contained the provision in the curriculum that "Mathematics and Astrology are to be given in three years, the first, Astrology, the second, Euclid, Ptolemy or Copernicus ad vota audientium," which also indicates, as Vicente de la Fuente points out, that at this University "the choice of the subject-matter to be taught lay not with the teachers but with the students, a rare situation."[194] One wonders what happened there when the professors and students received word[195] from the Cardinal Nuncio at Madrid in 1633 that the Congregations of the Index had decreed the Copernican doctrine was thereafter in no way to be held, taught or defended.
One of the graduates of this University, Father Zuñiga,[196] (better known as Didacus à Stunica), wrote a commentary on Job that was licensed to be printed in 1579, but was not published until 1584 at Toledo. Another edition appeared at Rome seven years later. It evidently was widely read for it was condemned donec corrigatur by the Index in 1616 and the mathematical literature of the next half century contains many allusions to his remarks on Job: IX: 6; "Who shaketh the earth out of her place, and the pillars thereof tremble." After commenting here upon the greater clarity and simplicity of the Copernican theory, Didacus à Stunica then states that the theory is not contradicted by Solomon in Ecclesiastes, as that "text signifieth no more but this, that although the succession of ages, and generations of men on earth be various, yet the earth itself is still one and the same, and continueth without any sensible variation" ... and "it hath no coherence with its context (as Philosophers show) if it be expounded to speak of the earth's immobility. The motion that belongs to the earth by way of speech is assigned to the sun even by Copernicus himself, and those who are his followers.... To conclude, no place can be produced out of Holy Scriptures which so clearly speaks the earth's immobility as this doth its mobility. Therefore this text of which we have spoken is easily reconciled to this opinion. And to set forth the wonderful power and wisdom of God who can indue the frame of the whole earth (it being of monstrous weight by nature) with motion, this our Divine pen-man added; 'And the pillars thereof tremble:' As if he would teach us, from the doctrine laid down, that it is moved from its foundations."[197]
French thinkers, like the English, did not encourage the new doctrine at this time. Montaigne[198] was characteristically indifferent: "What shall we reape by it, but only that we neede not care which of the two it be? And who knoweth whether a hundred yeares hence a third opinion will arise which happily shall overthrow these two præcedent?" The famous political theorist, Jean Bodin, (1530-1596), was as thoroughly opposed to it as DuBartas had been. In the last year of his life, Bodin wrote his Universæ Naturæ Theatrum[199] in which he discussed the origin and composition of the universe and of the animal, vegetable, mineral and spiritual kingdoms. These five books (or divisions) reveal his amazing ideas of geology, physics and astronomy while at the same time they show a mind thoroughly at home in Hebrew and Arabian literature as well as in the classics. His answer to the Copernican doctrine is worth quoting to illustrate the attitude of one of the keenest thinkers in a brilliant era:
"Theorist: Since the sun's heat is so intense that we read it has sometimes burned crops, houses and cities in Scythia,[200] would it not be more reasonable that the sun is still and the earth indeed revolves?
"Mystic: Such was the old idea of Philolaus, Timæus, Ecphantes, Seleucus, Aristarchus of Samos, Archimedes and Eudoxus, which Copernicus has renewed in our time. But it can easily be refuted by its shallowness although no one has done it thoroughly.
"The.: What arguments do they rely on who hold that the earth is revolved and that the sun forsooth is still?
"Mys.: Because the comprehension of the human mind cannot grasp the incredible speed of the heavenly spheres and especially of the tenth sphere which must be ten times greater than that of the eighth, for in twenty-four hours it must traverse 469,562,845 miles, so that the earth seems like a dot in the universe. This is the chief argument. Besides this, we get rid entirely of epicycles in representing the motions of the planets and what is taught concerning the motion of trepidation in the eighth sphere vanishes. Also, there is no need for the ninth and tenth spheres. There is one argument which they have omitted but which seems to me more efficacious than any, viz.: rest is nobler than movement, and that celestial and divine things have a stable nature while elemental things have motion, disturbance and unrest; therefore it seems more probable that the latter move rather than the former. But while serious absurdities result from the idea of Eudoxus, far more serious ones result from that of Copernicus.
"The.: What are these absurdities?
"Mys.: Eudoxus knew nothing of trepidation, so his idea seems to be less in error. But Copernicus, in order to uphold his own hypothesis, claims the earth has three motions, its diurnal and annual ones, and trepidation; if we add to these the pull of weight towards the center, we are attributing four natural motions to one and the same body. If this is granted, then the very foundations of physics must fall into ruins; for all are agreed upon this that each natural body has but one motion of its own, and that all others are said to be either violent or voluntary. Therefore, since he claims the earth is agitated by four motions, one only can be its own, the others must be confessedly violent; yet nothing violent in nature can endure continuously. Furthermore the earth is not moved by water, much less by the motion of air or fire in the way we have stated the heavens are moved by the revolutions of the enveloping heavens. Copernicus further does not claim that all the heavens are immobile but that some are moved, that is, the moon, Mercury, Venus, Mars, Jupiter and Saturn. But why such diversity? No one in his senses, or imbued with the slightest knowledge of physics, will ever think that the earth, heavy and unwieldy from its own weight and mass, staggers up and down around its own center and that of the sun; for at the slightest jar of the earth, we would see cities and fortresses, towns and mountains thrown down. A certain courtier Aulicus, when some astrologer in court was upholding Copernicus's idea before Duke Albert of Prussia, turning to the servant who was pouring the Falernian, said: "Take care that the flagon is not spilled."[201] For if the earth were to be moved, neither an arrow shot straight up, nor a stone dropped from the top of a tower would fall perpendicularly, but either ahead or behind. With this argument Ptolemy refuted Eudoxus. But if we search into the secrets of the Hebrews and penetrate their sacred sanctuaries, all these arguments can easily be confirmed; for when the Lord of Wisdom said the sun swept in its swift course from the eastern shore to the west, he added this: Terra vero stat æternam. Lastly, all things on finding places suitable to their natures, remain there, as Aristotle writes. Since therefore the earth has been alloted a place fitting its nature, it cannot be whirled around by other motion than its own.
"The.: I certainly agree to all the rest with you, but Aristotle's law I think involves a paralogism, for by this argument the heavens should be immobile since they are in a place fitting their nature.
"Mys.: You argue subtly indeed, but in truth this argument does not seem necessary to me; for what Aristotle admitted, that, while forsooth all the parts of the firmament changed their places, the firmament as a whole did not, is exceedingly absurd. For either the whole heaven is at rest or the whole heaven is moved. The senses themselves disprove that it is at rest; therefore it is moved. For it does not follow that if a body is not moved away from its place, it is not moved in that place. Furthermore, since we have the most certain proof of the movement of trepidation, not only all the parts of the firmament, but also the eight spheres, must necessarily leave their places and move up and down, forward and back."[202]
This was the opinion of a profound thinker and experienced man of affairs living when Tycho Brahe and Bruno were still alive and Kepler and Galileo were beginning their astronomical investigations. But he was not alone in his views, as we shall see; for at the close of the sixteenth century, the Copernican doctrine had few avowed supporters. The Roman Church was still indifferent; the Protestants clinging to the literal interpretation of the Bible were openly antagonistic; the professors as a whole were too Aristotelian to accept or pay much attention to this novelty, except Kepler and his teacher Mæstlin (though the latter refused to uphold it in his textbook);[203] while astronomers and mathematicians who realized the insuperable objections to the Ptolemaic conception, welcomed the Tychonic system as a via media; and the common folk, if they heard of it at all, must have ridiculed it because it was so plainly opposed to what they saw in the heavens every day. In the same way their intellectual superiors exclaimed at the "delirium" of those supporting such a notion.[204] One thinker, however was to see far more in the doctrine than Copernicus himself had conceived, and by Giordano Bruno the Roman Church was to be aroused.
WHEN the Roman Catholic authorities awoke to the dangers of the new teaching, they struck with force. The first to suffer was the famous monk-philosopher, Giordano Bruno, whose trial by the Holy Office was premonitory of trouble to come for Galileo.[205]
After an elementary education at Naples near his birth-place, Nola,[206] Filippo Bruno[207] entered the Dominican monastery in 1562 or 1563 when about fourteen years old, assuming the name Giordano at that time. Before 1572, when he entered the priesthood, he had fully accepted the Copernican theory which later became the basis of all his philosophical thought. Bruno soon showed he was not made for the monastic life. Various processes were started against him, and fleeing to Rome he abandoned his monk's garments and entered upon the sixteen years of wandering over Europe, a peripatetic teacher of the philosophy of an infinite universe as deduced from the Copernican doctrine and thus in a way its herald.[208] He reached Geneva in 1579 (where he did not accept Calvinism as was formerly thought),[209] but decided before many months had passed that it was wise to depart elsewhere because of the unpleasant position in which he found himself there. He had been brought before the Council for printing invectives against one of the professors, pointing out some twenty of his errors. The Council sent him to the Consistory, the governing body of the church, where a formal sentence of excommunication was passed against him. When he apologized it was withdrawn. Probably a certain stigma remained, and he left Geneva soon thereafter with a warm dislike for Calvinism. After lecturing at the University of Toulouse he appeared in Paris in 1581, where he held an extraordinary readership. Two years later he was in England, for he lectured at Oxford during the spring months and defended the Copernican theory before the Polish prince Alasco during the latter's visit there in June.[210]
To Bruno belongs the glory of the first public proclamation in England of the new doctrine,[211] though only Gilbert[212] and possibly Wright seem to have accepted it at the time. Upon Bruno's return to London, he entered the home of the French ambassador as a kind of secretary, and there spent the happiest years of his life till the ambassador's recall in October, 1585. It was during this period that he wrote some of his most famous books. In La Cena de la Ceneri he defended the Copernican theory, incidentally criticising the Oxford dons most severely,[213] for which he apologized in De la Causa, Principio et Uno. He developed his philosophy of an infinite universe in De l'Infinito e Mondi, and in the Spaccio de la Bestia Trionphante "attacked all religions of mere credulity as opposed to religions of truth and deeds."[214] This last book was at once thought to be a biting attack upon the Roman Church and later became one of the grounds of the Inquisition's charges against him. During this time in London also, he came to know Sir Philip Sydney intimately, and Fulk Greville as well as others of that brilliant period. He may have known Bacon;[215] but it is highly improbable that he and Shakespeare met,[216] or that Shakespeare ever was influenced by the other's philosophy.[217]
Leaving Paris soon after his return thither, Bruno wandered into southern Germany. At Marburg he was not permitted to teach, but at Wittenberg the Lutherans cordially welcomed him into the university. After a stay of a year and a half, he moved on to Prague for a few months, then to Helmstadt, Frankfort and Zurich, and back to Frankfort again where, in 1591, he received an invitation from a young Venetian patrician, Mœcenigo, to come to Venice as his tutor. He re-entered Italy, therefore, in August, much to the amazement of his contemporaries. It is probable that Mœcenigo was acting for the Inquisition.[218] At any rate, he soon denounced Bruno to that body and in May, 1592, surrendered him to it.[219]
In his trial before the Venetian Inquisition,[220] Bruno told the story of his life and stated his beliefs in answer to the charges against him, based mainly on travesties of his opinions. In this statement as well as in La Cena de le Ceneri, and in De Immenso et Innumerabilis,[221] Bruno shows how completely he had not merely accepted the Copernican doctrine, but had expanded it far beyond its author's conception. The universe according to Copernicus, though vastly greater than that conceived by Aristotle and Ptolemy, was still finite because enclosed within the sphere of the fixed stars. Bruno declared that not only was the earth only a lesser planet, but "this world itself was merely one of an infinite number of particular worlds similar to this, and that all the planets and other stars are infinite worlds without number composing an infinite universe, so that there is a double infinitude, that of the greatness of the universe, and that of the multitude of worlds."[222] How important this would be to the Church authorities may be realized by recalling the patristic doctrine that the universe was created for man and that his home is its center. Of course their cherished belief must be defended from such an attack, and naturally enough, the Copernican doctrine as the starting point of Bruno's theory of an infinite universe was thus brought into question;[223] for, as M. Berti has said,[224] Bruno's doctrine was equally an astro-theology or a theological astronomy.
The Roman Inquisition was not content to let the Venetian court deal with this arch heretic, but wrote in September, 1592, demanding his extradition. The Venetian body referred its consent to the state for ratification which the Doge and Council refused to grant. Finally, when the Papal Nuncio had represented that Bruno was not a Venetian but a Neapolitan, and that cases against him were still outstanding both in Naples and in Rome, the state consented, and in February of the next year, Bruno entered Rome, a prisoner of the Inquisition. Nothing further is known about him until the Congregations took up his case on February 4th, 1599. Perhaps Pope Clement had hoped to win back to the true faith this prince of heretics.[225] However Bruno stood firm, and early in the following year he was degraded, sentenced and handed over to the secular authorities, who burned him at the stake in the Campo di Fiori, February 17, 1600.[226] All his books were put on the Index by decree of February 8, 1600, (where they remain to this day), and as a consequence they became extremely rare. It is well to remember Bruno's fate, when considering Galileo's case, for Galileo[227] was at that time professor of mathematics in the university of Padua and fully cognizant of the event.
Galileo's father, though himself a skilled mathematician, had intended that his son (born at Pisa, February 15, 1564), should be a cloth-dealer, but at length permitted him to study medicine instead at the university of Pisa, after an elementary education at the monastery of Vallombrosa near Florence. At the Tuscan Court in Pisa, Galileo received his first lesson in mathematics, which thereupon became his absorbing interest. After nearly four years he withdrew from the university to Florence and devoted himself to that science and to physics. His services as a professor at this time were refused by five of the Italian universities; finally, in 1589, he obtained the appointment to the chair of physics at Pisa. He became so unpopular there, however, through his attacks on the Aristotelian physics of the day, that after three years he resigned and accepted a similar position at Padua.[228] He remained here nearly eighteen years till his longing for leisure in which to pursue his researches, and the patronage of his good friend, the Grand Duke of Tuscany, brought him a professorship at the university of Pisa again, this time without obligation of residence nor of lecturing. He took up his residence in Florence in 1610; and later (1626), purchased a villa at Arcetri outside the city, in order to be near the convent where his favorite daughter "Suor Maria Celeste" was a religious.[229]
During the greater part of his lectureship at Padua, Galileo taught according to the Ptolemaic cosmogony out of compliance with popular feeling, though himself a Copernican. In a letter to Kepler (August 4, 1597)[230] he speaks of his entire acceptance of the new system for some years; but not until after the appearance of the New Star in the heavens in 1604 and 1605, and the controversy that its appearance aroused over the Aristotelian notion of the perfect and unchangeable heavens, did he publicly repudiate the old scheme and teach the new. The only information we have as to how he came to adopt the Copernican scheme for himself is the account given by "Sagredo," Galileo's spokesman in the famous Dialogue on the Two Principal Systems (1632):