1616

by Christensen, Thomas

  Galileo was charismatic, and he won a following at Padua as a brilliant and inspiring lecturer, though he also ruffled feathers among the senior faculty. Unlike Kepler, Galileo was supremely confident and self-assured — smug and arrogant, his enemies would say. But that did not mean he was as rash and imprudent as Giordano Bruno, who had been burned at the stake in the Campo dei Fiori in Rome in February 1600 for holding heretical beliefs. (The inquisitor for Bruno’s trial was Cardinal Bellarmine, who would later play a similar role in Galileo’s trial; Bellarmine was canonized in 1930.) Bruno was a pantheist and a Copernican. In his audacious, inspired vision of an infinite universe, “there are innumerable suns, and an infinite number of earths revolve around these suns, just as the seven we can observe revolve around this sun that is close to us.” Galileo wasn’t looking for trouble, but his caustic and condescending attitude to his detractors helped fan its fires.

  His life was changed by a technological breakthrough. Around 1608, a team of Dutch spectacle makers ground lenses and arranged them in a tube in such a way that they magnified objects viewed. These first devices magnified only by a power of about three or four, but this was enough to cause a good deal of excitement. In London, Thomas Harriot bought one of the instruments and, inspired by an appearance of Halley’s comet in 1607, trained it on the moon; he would be the first person to produce a drawing from astronomical observation through a telescope. He was a member of the so-called School of Night, a group of reputedly atheistic freethinkers centered around Walter Raleigh. Harriot served as Raleigh’s mathematics tutor and accountant, and he advised him on shipbuilding and such theoretical questions as the most efficient way to stack cannonballs. As a young man he traveled to Roanoke Island on an expedition organized by Raleigh and reportedly learned the Algonquian language. He corresponded with Kepler, but his mathematical and astronomical discoveries did not become widely known because of his failure to publish.

  Calculating Device, about 1606, by Galileo Galilei. Brass, 26 × 36 cm. © Museo Galileo, inv. 2430.

  Measurement and calculation were the essence of Galileo’s approach to science. Near the turn of the century, pressed by debts — his sister’s dowry, his brother’s wedding — Galileo turned to the manufacture of a sort of super slide rule /compass of his invention, produced in collaboration with a toolmaker trained at the Arsenale in Venice. It was intially marketed as an aid to military caculations and later expanded to a variety of other uses. He further profited by offering instruction in the device’s use.

  A former pupil of Galileo’s sent word to Venice about the new instrument, and Galileo immediately realized its military potential. Then, in August 1609, a Dutchman showed up in Padua proposing to sell the device to the doge of Venice. This Galileo managed to prevent with some fast talking, downplaying the Dutchman’s product and assuring the Venetians that he could produce a much better version. Having bought a little time, he returned to Padua and succeeded in producing a telescope in only a day (he said), a remarkable feat of reverse engineering. More important, he continued to refine the instrument until he had achieved a magnification around the equivalent of common modern binoculars; later he would improve the optics even further. His telescope was a triumph not only of his skill at applied science but also of the glasswork and craftsmanship of the artisans of the Veneto.

  Galileo demonstrated his leather-tooled, yard-long telescope — which he called a “perspicillium” — to the doge and his counselors, showing how approaching ships could be detected hours before they could be seen by the naked eye. The demonstration was a resounding success, and Galileo was rewarded with a doubled salary, a handsome bonus, and a lifetime appointment at the University of Padua. He had it made.

  Like Harriot, Galileo began to turn his telescopic attentions skyward. Among his discoveries were moons orbiting Jupiter, which could be identified by the way they changed their positions from day to day relative to the planet. With unprecedented clarity this discovery gave the lie to the conventional notion that the universe was a sort of giant snow globe in which celestial objects were fixed to a crystal sphere and could not move independently. The book that he published in 1610 about his observations, The Starry Messenger, made him an international celebrity, though a controversial one. Kepler published an article of support and later obtained a telescope with which he was able to confirm the Jupiter observations. Galileo was hailed as a discoverer comparable to Columbus and Magellan. The Scottish poet Thomas Seggett, for example, wrote:

  Columbus gave man lands to conquer by bloodshed,

  Galileo new worlds harmful to none.

  Which is better?

  But to academic philosophers whose livelihood depended on teaching the traditional Aristotelian dogma, Galileo’s discoveries did not seem harmless. They claimed the moons and other celestial discoveries were optical illusions created by the telescope itself. They labeled Galileo a charlatan, an attention-seeking fraud. Some looked through his telescope but denied seeing the objects Galileo said were there. Others, like Cesare Cremonini, the leader of the Aristotelian faction at Padua, and Giulio Libri, a professor of philosophy at Pisa, simply refused to look through the glass at all. Christopher Clavius, a Jesuit mathematician in Rome, said that the apparent roughness of the moon must be an optical illusion — perhaps its apparent unevenness was smoothed over by a perfect transparent crystal.

  Then the philosophers went further. Not only was Galileo’s radical new astronomy erroneous and fraudulent, they began to claim, but it was also heretical. If the earth was not unique, how could the people on other planets have descended from Adam and Eve? What would be the meaning of the Flood? In Florence this faction was led by a man named Ludovico delle Colombe. Colombe means “dove,” so Galileo began to dismiss his critics by referring to them as the Pigeon League. He wasn’t concerned, he said: “Since the malicious league is few in number I laugh at it.”

  Pages from The Starry Messenger, 1610, by Galileo Galilei.

  Galileo’s telescopic observations of the movements of the moons of Jupiter made The Starry Messenger a sensation. The diagrams on these pages from the book chart the changing positions of the moons relative to the planet. These observations proved that some celestial objects orbitted others: the heavens were not permanently affixed to a vast celestial sphere revolving day by day about the earth.

  But an academic establishment doesn’t become established without having influential connections. It found a receptive ear in the priests who recalled the divisions the Protestant revolution had caused in the church. The new science seemed to them to be another threat to religion. A young priest in Florence denounced Galileo — along with science in general — from the pulpit. Things continued to build until Pope Paul V himself pronounced the stability of the sun and the movement of the earth to be contrary to scripture.

  It all came to a head in February 1616. A formal accusation had been lodged against Galileo, and the Inquisition was obliged to investigate it. Faced with these worrisome developments, against the advice of his friends, Galileo decided at the end of 1615 to travel to Rome and argue the matter on his own behalf. Though in poor health, he exuded confidence in his ability to set matters straight through the superiority of his reasoning and the strength of his argumentation. Arriving in Rome, he immediately set about making speeches, debating opponents, and meeting with church officials. His main argument was that religion and science should be kept separate — for the good of the church. If religious leaders took positions on science, he argued, the church itself would be damaged should observational research prove them wrong. Better to concentrate on the moral, the higher, the truer sense of the Bible than to read it literally in a misguided effort to settle issues best left to science.

  To Galileo’s astonishment, however, he found that this argument, which he thought the clincher, was turning out to be a hard sell. Apart from the argument’s merits, his right even to advance it was questioned — if the Reformation had made one thing clear it was that issues wi
th theological implications should be left to theologians. No matter how brilliant Galileo was and how persuasively he argued, the taint of the unorthodox was starting to hang about him, and many influential persons he tried to meet suddenly seemed always to be in meetings or out of town: perhaps he could leave a message with their assistants? Meanwhile, his case, and specifically the issue of Copernicanism, had been referred by the Inquisition to a committee of “Qualifiers,” to determine whether they were contrary to the teachings of the church. In February the Qualifiers returned the following verdicts on the two main points:

  1 That the sun is in the center of the world, and totally immovable as to locomotion: Censure. All say that the said proposition is foolish and absurd in Philosophy, and formally heretical inasmuch as it contradicts the express opinion of Holy Scriptures in many places, according to the words themselves and according to the common expositions and meanings of the Church fathers and doctors of theology.

  2 That the earth is neither in the center of the world nor immovable but moves as a whole and in daily motion: Censure. All say this proposition receives the same censure in Philosophy, and with regard to Theological verity it is at least erroneous in the faith.

  Galileo was then called to a meeting with Cardinal Bellarmine to receive this ruling. What exactly happened in this meeting has long been debated, as his later trial would hinge on it. Apparently Bellarmine had been instructed by the pope to inform Galileo that it was not permissible to “hold or defend” the offending beliefs. If Galileo resisted this directive he was to be further enjoined against teaching them — that is, of presenting them as one line of thought among others without holding or defending them; in other words, without passing judgment on their validity.

  Galileo saw how things stood, and he didn’t resist. In fact, he even asked for and received a document from Bellarmine specifying that he had not received any sort of personal reprimand; the ruling was not aimed specifically at him but was directed to the whole Catholic world. This document would be a major piece of evidence during his trial for heresy in 1633. Although Galileo had mostly steered clear of these controversial subjects for two decades, his investigations into such questions as the cause of tides had eventually brought him back again to the issue of heliocentrism, and he published his thoughts on the subject in a daring book called Dialogue Concerning the Two Chief Systems of the World: Ptolemaic and Copernican. The new pope, Urban VIII, though at one time friendly with Galileo, saw this provocation as a deliberate personal betrayal. Galileo was again teaching Copernicanism. At his trial Galileo produced the document that Bellarmine had given him, but this was countered by a document the Inquisition produced indicating that he had been enjoined not only against holding and defending the prohibited beliefs but also teaching them. Galileo denied that he had been prohibited from teaching, and the Inquisition’s document was unsigned. On the weight of evidence Galileo’s signed document should have trumped the other one, but he had angered the top papal authorities, and he was found guilty. Galileo prudently admitted having “gone too far,” and hoped thereby for a light sentence, but these hopes were dashed. He would spend the rest of his life under house arrest, he was prohibited from all further publishing, and all of his books were placed on the Index of prohibited publications

  Galileo’s case had begun as a dispute with academic philosophers, for whom grand conceptualizing held more value than menial observation. Applied science, such as Galileo specialized in, was considered mere technology; true science, they felt, concerned itself with the ultimate causes of things, not the quirks of their everyday mundane expression. This was a debate that Galileo was fully capable of waging. Unfortunately for him, however, the rifts caused by Luther and others in what had once appeared (deceptively) to be a monolithic European religion had made the Catholic church extremely sensitive to deviation from doctrine. Faced with the Protestant threat — which had resulted in a considerable loss of income from northern parishes — the church was fighting back. With the establishment of the Jesuit order and the standardization of religious thought following the Council of Trent, the church was now on the offensive. The effectiveness of its Counter-Reformation depended, it felt, on standing firm against any further deviant or subversive beliefs.

  Applying this line of thought to the case of Galileo resulted in a disaster for the church’s public relations. Many historians of science today emphasize that Galileo’s troubles were largely caused by his own difficult personality. They caution against the assumption that science and religion were necessarily at odds. Still, for centuries following his trial and condemnation, despite its protests to the contrary, the church would find it hard to shake the charge of being opposed to science. Not until the mid-seventeenth century did it remove Galileo’s works from the Index so they could be read. Catholic schools were prohibited from teaching that the earth orbits the sun until well into the eighteenth century. As late as the mid-twentieth century the church was still censoring biographies of Galileo. Finally, in 1992, Pope John Paul II issued a statement that seemed to exonerate the scientist. But Cardinal Paul Poupard, chairman of the Galileo pardon board, in an interview with James Reston, Jr., clarified that the statement was not an apology, it was merely a “formal recognition” of error.

  Pages from Kepler’s Calculations, early seventeenth century.

  In calculating the orbit of Mars, Kepler lacked advanced mathematical tools, but he was dogged in pursuing the answers he sought.

  Kepler’s working calculations on the orbit of Mars take up nine hundred pages in a minuscule hand. How many more pages would he have needed if he had had to make his calculations using Roman numerals? It is no longer possible to see the Scientific Revolution as a self-contained European phenomenon; exchange of ideas between Islamic West Asia and Christian Europe was a lively and vital component of the new scientific discoveries.

  Kepler had been an enthusiastic Copernican since his student days, when his embrace of heliocentrism was probably more intuitive than rational. Galileo was a more reluctant Copernican, who tried to avoid addressing the issue until led to confront it through his astronomical observations and other research. Two other major figures of the European scientific revolution from this same period, Simon Stevin, a pioneer of hydrostatics, and William Gilbert, one of the fathers of electrical engineering, were also Copernicans. Social theorist Howard Margolis, author of It Started With Copernicus, has proposed that Copernicanism enabled original thinking by encouraging a similar rethinking of other established beliefs. But, in all likelihood, none of the four scientists realized that Copernicus, who had published his groundbreaking book On the Revolutions of the Celestial Spheres just before his death in 1543, had been significantly influenced by Islamic astronomical research made centuries before his lifetime.

  In 1957 Otto Neugebauer, a scholar researching Copernicus, happened on some diagrams by the fourteenth-century astronomer Ibn al-Shatr, and he recognized that they were identical to some in Copernicus’ work. Later he found that Copernicus had also relied on the work of Nasir al din al-Tusi, an even earlier astronomer, who had tried to revise traditional Ptolemaic astronomical theory to make it better conform to actual observation. (The ancient Aristotelian and Ptolemaic astronomical theory had spread east through Byzantium — the Byzantine capital of Constantinople was conquered by the Ottomans in 1453 and renamed Istanbul — into Islamic lands, as well as north and west through Europe. Even earlier, many Greek thinkers had relocated to Iran after Christians closed the Platonic academy in Athens.) It was subsequently discovered that Copernicus had even used the same letters as al-Tusi to designate the points in a key diagram, removing any lingering doubt that Copernicus had access to the work of Muslim astronomers. (Evidence for Copernicus’s reliance on the work of early Islamic astronomers is summarized by George Saliba in his Islamic Science and the Making of the European Renaissance.) How Copernicus was exposed to these Islamic scientists’ works is unknown, but the likeliest explanation is that he found eithe
r a native Arabic speaker or else a Renaissance Arabist to report their contents to him, though the exact texts he consulted remain unclear.

  An Astrologer Surrounded by His Equipment, early seventeenth century (detail). Marginal illustration from Jahangir’s album, 420 × 625 cm (full page). Naprstek Museum, Prague.

  Interest in astrology stimulated development of scientific instruments such as the astrolabe. The simple mariner’s astrolabe measured the height of the sun above the horizon to figure latitude. More complicated planispheric astrolabes combined a fixed part, representing the sky viewed from a certain latitude, with a movable part simulating the daily apparent motion of the sky. These astrolabes work on the principle that if you know the time you can locate celestial bodies, and if you can identify celestial bodies you can determine the time. By lining up the movable part with an observed celestial object the user can consult a chart based on the angle of the object in the sky to figure the desired result.

  A remarkable Arabic publishing operation was funded by Cardinal Ferdinand de Medici, Duke of Tuscany, in Italy in the late sixteenth century. The Medici Oriental Press — relying on the library of a Turkish scholar who had fled a dispute in his homeland, arrived at Venice around 1577, and converted to Christianity — published a number of Arabic-language books. Among those publications was one based on the work of Nasir al-Din al-Tusi, one of the astronomers whose work Copernicus drew upon. There was sufficient interest in Arabic in Europe that, sometime around 1616, it was proposed that the language be taught for the benefit of medical students at Herborn Academy in Germany.