by Dava Sobel
Reinhold immediately began constructing new tables of planetary data, based entirely on Copernicus’s devices. Although Copernicus had provided various tables in On the Revolutions, many of the numbers needed for calculating planetary positions lay scattered throughout the text. Reinhold gathered all this information into convenient form for working astronomers—that is, for astrologers. Melanchthon blessed Reinhold’s effort, then enlisted financial backing for its publication from Duke Albrecht, who obliged. It seemed only fitting that Reinhold name his project the Prutenic Tables, in honor of Prussia, home to both Copernicus and Albrecht.
No one can say what effect Rheticus might have exerted on the Wittenberg scholars had he remained among them, but it seems unlikely he could have defended Copernicus’s cosmos against the criticisms of Luther and Melanchthon. Absent Rheticus, Copernicus’s intent, which had already suffered the undermining of Osiander’s note to readers, underwent further subversions at Wittenberg. Reinhold’s published Tables meshed the planetary models with a stationary, central Earth. Peucer, in his book Hypotheses astronomicae, reinstated the ninth and tenth spheres beyond the fixed stars.
After two years at Leipzig, Rheticus, restless again, left his students without permission in the autumn of 1545 to visit the mathematician and astrologer Girolamo Cardano in Milan. Rheticus took along a gift copy of Copernicus’s book, which he inscribed to Cardano when he arrived.
The two had previously collaborated by correspondence on a collection of genitures (horoscopes) of famous men, published by Petreius in the same year as On the Revolutions. Now Cardano was preparing an enlarged new edition, and Rheticus gave him several detailed horoscopes for inclusion. One concerned Andreas Vesalius, the physician whose 1543 masterpiece, On the Fabric of the Human Body, had corrected ancient misconceptions, thereby doing for anatomy what On the Revolutions did for astronomy. Another geniture sketched the character and life circumstances of the mathematical prodigy Johannes Regiomontanus, who wrote the Epitome of Ptolemy’s Almagest—the book Copernicus had studied so closely in his youth.
Rheticus also delivered Osiander’s horoscope to Cardano at this time. He had come with the hope that Cardano might help him in return, perhaps as a collaborator on the great project Rheticus envisioned about the science of triangles. Instead, Rheticus found Cardano trapped in the triangular compartments of his horoscope diagrams, extracting the most detailed predictions from them, down to the manner of a man’s death and the disposition of his corpse. While these techniques surely fascinated Rheticus, his Milan sojourn soured under Cardano’s personal slights and lukewarm response to On the Revolutions.
That summer, Leipzig summoned Rheticus back to his teaching duties after the year’s unauthorized absence. He left Italy for Leipzig in autumn 1546 but stopped en route in Lindau, where he suffered a mysterious nervous and physical breakdown that deranged him for several months. Fortunately his former Wittenberg classmate Caspar Brusch, the Lindau schoolmaster, looked after Rheticus and later recounted his ordeal in a letter to a mutual friend of theirs:
“He has halfway regained his former state of health (after having been, while here with me, severely ill), though he is not yet fully recovered. … I know that something about an evil spirit has been rumored abroad by commercial travelers. Even if this report is not quite false or devoid of substance, still Joachim is taking it very hard, since he is apprehensive that it could somewhat damage his former reputation.” Rheticus’s mother, a Catholic, also lived in the area, in Bregenz, with her wealthy second husband. She urged her son to seek release from his demons by making a pilgrimage to St. Eustatius’s shrine in Alsace, but he refused.
“He lay ill here for nearly five months,” Brusch continued in his letter of late August 1547, “and every day I would visit, conversing and fellowshipping with him. Throughout this time I made available to him the whole Bible, in both German and Latin, from my library, as well as many of the devotional writings of Luther, Melanchthon, and Cruciger. These he read and reread so diligently that in the end he knew them through and through. However, on particular occasions, with a full heart and most fervent vows, indeed often in tears, he would call upon the Son of God, awaiting deliverance from him alone.”
When his crisis passed, Rheticus further postponed his return to Leipzig by spending the winter in Zurich, still striving to recover his health. While there, he wrote a proposal for improving the triquetrum, now that the observational instrument was enjoying a new vogue in the wake of On the Revolutions. Copernicus had apparently “stimulated certain eminent men to observe the motions of the heavenly bodies,” Rheticus said. He published his triquetrum suggestion in Zurich, in February 1548, but dedicated it “to the teachers and professors of the faculty of arts at the University of Leipzig.” That same month, on February 13, he wrote to them directly, saying he would see them before long. On the sixteenth, he turned thirty-four—surprised, perhaps, to find himself still alive. He spent Easter in Baden, bathing in the thermal springs on his doctor’s advice, and finally reentered Leipzig at summer’s end. As happened when he returned to Wittenberg following his first protracted leave, he found the deanship of the Faculty of Arts thrust upon him.
Despite the duties of administration and teaching, Rheticus rebounded during this period. In October 1549, he wrote to Giese to report progress on several new works relevant to astronomy. He hoped his soon-to-be-published calendar of prognostications for the coming year would sell well enough to fund his private researches on more serious topics. For example, he had just completed a modern scientific commentary on the geometry classic, Euclid’s Elements, and would soon issue his Ephemerides: A Setting Forth of the Daily Position of the Stars … by Georg Joachim Rheticus according to the theory … of his teacher Nicolaus Copernicus of Torun. He never tired of reminding readers that it was Copernicus “whose hand advanced the machinery of this world.” As heir to that tradition, “I have not wanted to backslide from Copernican teaching, not even by a finger’s width.”
Through his resumed communication with Giese, Rheticus discovered Dantiscus had died and ceded the Varmia bishop’s seat to his old rival. But Giese lasted only a year in that pinnacle position, before his own death in October 1550, at age seventy. Then Stanislaw Hozjusz, Dantiscus’s chosen, took over as Bishop of Varmia, and fought so strenuously against the Lutheran heresy—even winning some prominent converts back to Catholicism—that he was elevated to cardinal.
At the start of 1551, Rheticus chose the word canon—reminiscent of Copernicus, but also signifying a code of instructions—for the title of his pamphlet Canon of the Science of Triangles. It offered the best available trigonometric tables—crucial calculation aids for astronomers. Lest anyone miss this slim volume’s relation to Copernicus, Rheticus cemented the connection in a playful introductory dialogue between “Philomathes,” a lover of math, and his guest “Hospes.” When Hospes asks, “What sort of man is this Rheticus?” Philomathes replies, “He indeed is the one who is now delivering to us this fruit from the most delightful gardens of Copernicus. For after his recent return from Italy he resolved to impart freely to students of mathematics everything he learned from that excellent old man, as well as everything he has acquired by means of his own effort, perseverance, and devotion.”
The question “What sort of man is this Rheticus?” came up again in the spring of 1551, when the father of a Leipzig student charged that the professor had perpetrated “a sudden, outrageous, and unchristian” act on his son. After luring the boy, “a minor child” in his father’s eyes, Rheticus allegedly “plied him with strong drink, until he was inebriated; and finally did with violence overcome him and practice upon him the shameful and cruel vice of sodomy.”
The legal punishment for the crime of sodomy was “death by fire.” Guilty or no, Rheticus ran away in April, before the winter term ended or his criminal trial could begin. Rumors placed him in Prague. Numerous urgent letters in fact reached him there, summoning his appearance in court, but Rheticus
never returned to Leipzig. After months of fruitless maneuvering, the university sentenced him in absentia to banishment for a period of 101 years. In recognition of his talents, however, and for the sake of decorum, the particulars of his accusation and sentencing were kept confidential.
Rheticus spent that first year in Prague studying medicine at Charles University, and probably the next year as well. Then he continued his medical training in Silesia through 1554. He seems to have seen medicine as the ideal means to guarantee himself an income for as long as he remained unattached to an academic position and without the support of a patron. Then, too, medicine had been his father’s profession, and that of Copernicus as well.
“Doctor” Rheticus moved to Krakow in the spring of 1554. He chose the city for its geographical location, three hundred miles due south of Frauenburg, which connected him to Copernicus by a mapmaker’s meridian. He resided there for nearly two decades (longer than he ever lived anywhere else), pursuing his old career and his new one simultaneously. On July 20 he wrote to a former student, “I have erected a fifty-foot obelisk in a perfectly level field that the marvelous Mr. Johannes Boner has made available to me for this purpose. By this means, God willing, I shall describe anew the whole sphere of the fixed stars.” He shared the work of computing the new, more precise tables he planned to publish with as many as five hired helpers at a time, dividing fractions of angles by a factor of ten billion. Thus engaged in Krakow, Rheticus realized one day that he was past forty, and that he must have erred in forecasting his early demise. The habit of living had gone on for so long, he believed he might reach old age after all. A decade later, in 1563, he “again picked up the work of Copernicus,” he said—referring to his teacher’s book, as opposed to his legacy—and considered “elucidating it with a commentary.”
Heinrich Petri of Basel, a distant relative of Johannes Petreius, published the second edition of On the Revolutions in 1566. It contained, in lieu of any new elucidating commentary by Rheticus, the third printing of the disciple’s original digest, or First Account. If ever Rheticus felt snubbed by lack of acknowledgment in the first edition of On the Revolutions, his role in it was here made manifest.
His face stayed hidden, however, and remains so even now. Any formal portrait of him, any sketch or caricature, must have been lost long ago. Despite his numerous publications and acquaintances, his university affiliations, his several occupations, and the curiosity that carried him to so many doors, he left no impression of his physical appearance.
In 1572, Rheticus moved one last time, south from Krakow to the Hungarian city of Cassovia, where a new patron waited to underwrite him. Rheticus persevered with his great opus on the science of triangles, but he was distracted by his medical interests, hampered by having lost important papers through his various relocations, and daunted by the mountain of calculation still to conquer. In a replay of life events he could never have anticipated, he opened his door one spring day in 1574 to a surprise visitor from Wittenberg, who had read Rheticus’s pamphlet about triangles (the Canon) and heard of his ambition to complete a larger work.
“We had hardly exchanged a few words on this and that,” the youth, Valentin Otto, later recalled, “when, on learning the cause of my visit he burst forth with these words: ‘You come to see me at the same age as I was myself when I visited Copernicus. If it had not been for my journey, his work would never have seen the light of day.’ ”
The similar stories diverge at that point. Although Otto proved the most devoted apprentice, he toiled only a short time alongside his teacher. After a few months, Rheticus sent Otto to Krakow to retrieve records he had left there. Returning November 28 from a harrowing journey through rain and flood (“Twice in one day I was in danger of drowning”), Otto found Rheticus critically ill. He tended to his mentor over the next several days, during which time Rheticus officially transferred to him the right—and the duty—to complete the Science of Triangles. Otto swore he would, and Rheticus died in his arms early on Saturday, December 4, 1574, at sixty years of age.
Spurred on by the great love he professed for Rheticus, Otto struggled through the next twenty years to complete his inherited endeavor. Almost as soon as the fifteen-hundred-page text appeared, in 1596, its many errors and insufficiencies revealed themselves. Otto had already grown senile, however, and could not rectify the text even when its problems were pointed out to him. A more worthy successor to the work later emerged in the person of Bartholomew Pitiscus, chaplain to the Prince Elector Frederick IV of Heidelberg. After Otto died in 1602, Pitiscus pored through the welter of disorganized notes he had accumulated. “I excavated them one page at a time from their state of neglect, filthy and almost putrid,” he said. Through the “irksome” work, he “gleaned many things that have delighted me wonderfully.” Pitiscus saw the final version of Rheticus’s contribution to the Copernican theory published in Frankfurt in 1613. He titled it Mathematical Treasury: or, Canon of Sines for a Radius of 1,000,000,000,000,000 Units … as Formerly Computed at Incredible Effort and Cost by Georg Joachim Rheticus.
Chapter 10
Epitome of Copernican Astronomy
I deem it my duty and task to advocate outwardly also, with all the powers of my intellect, the Copernican theory, which I in my innermost have recognized as true, and whose loveliness fills me with unbelievable rapture when I contemplate it.
—JOHANNES KEPLER, Epitome of Copernican Astronomy,
1617–21
Content with thePrutenic Tables, European astronomers took Copernicus at Osiander’s cautious word for the remainder of the sixteenth century—with two monumental exceptions. Between them, the flamboyant Tycho Brahe and the studious, passionately reverent Johannes Kepler carried Copernicus’s work to completion.
The Danish Tycho was literally star-struck in 1559, during his thirteenth summer, when a lunar eclipse illuminated the mathematics he was learning at a Lutheran university in Copenhagen. His noble birth gave him the means to purchase his own astronomy books, which he bought secretly, he said, and also read in secret, since his elders considered such pastimes beneath him. Soon he began logging his own observations of the planets and casting the horoscopes of famous men. At twenty-five, after losing most of his nose in a duel, he looked up one November night to see a nova’s explosion blaze suddenly to brilliance in the constellation Cassiopeia. He spoke of that 1572 event ever after as the moment when the heavens chose him to be their interlocutor.
“In truth, it was the greatest wonder that has ever shown itself in the whole of nature since the beginning of the world,” he announced in his hastily written book, De nova stella. Tycho’s new star indeed heralded a cataclysm. By its position in the heavens—too far from the zodiac to be a planet, too steadfast for a comet, and supralunar to boot—it boded the end of immutability in Aristotle’s celestial realms. Change could occur on high, Tycho’s careful observations showed, in the guise of a new star’s light. This claim competed for strangeness with Copernicus’s moving Earth—and perhaps Tycho winked at Copernicus when he compared the miracle of his Nova stella to Joshua’s stopping the Sun by prayer.
Tycho took his homeland’s far northern latitudes (worse than those bemoaned by Copernicus) as a proud birthright, and dedicated an early work to King Frederick of Denmark. While Tycho did allow that the extreme cold of the climate could disturb an astronomer’s serenity, it seems never to have deterred him. Five years after his nova discovery, in the early dark of another November night, Tycho stood fishing at a pond when a comet appeared to him. Its bright bluishwhite head and long ruddy tail—like a flame seen through smoke, he said—persisted through autumn into winter. That lengthy visitation gave Tycho time to prove that comets, though generally assumed to be quirks of the Earth’s atmosphere, actually traced paths among the planets. In contrast to contemporaries who feared the comet augured famine and pestilence, maybe even the death of a leader, Tycho confined its wrath to the heavens themselves. The Great Comet of 1577 condemned the ancient n
otion that solid celestial spheres carried the planets on their eternal rounds. Tycho saw plainly that no such structures impeded the comet’s free travel, and therefore concluded that no such structures existed. When he delivered this thunderbolt, one could almost hear the tinkle of shattering crystal.5
Tycho Brahe, Lord of Uraniborg.
Tycho’s admittedly nonacademic achievements soon gained him an adjunct faculty position at the University of Copenhagen, where he lectured briefly on Copernicus’s ideas and distributed the Prutenic Tables to his students. In addition to having read On the Revolutions, Tycho also acquired a handwritten copy of the Brief Sketch from a friend who had known Rheticus. Recognizing the mathematical importance of the document, Tycho made additional copies to distribute among other mathematicians, though he refused to accept the reality of the Earth’s motion. Bold as he was, and openly admiring of Copernicus, he stood firm on the stationary Earth. For, if the Earth truly pursued a great circle around the Sun, Tycho reasoned, then an Earthly observer would see the spaces between certain stars widen and narrow over the course of the year. He estimated the expected change, called parallax, at 7°, or about fifteen times the diameter of the full Moon. Tycho’s failure to perceive any parallax, even a tiny one, convinced him that no Earthly revolution took place. Copernicus’s explanation—that the stars’ tremendous distance precluded the perception of parallax—rang hollow to Tycho. Why, he asked, should the distance to the stars mushroom from Ptolemy’s ten thousand Earth diameters to the several million required by Copernicus? What purpose would all that emptiness serve? What’s more, stars visible across such immense gulfs would need to be absurdly large, perhaps bigger than the entire expanse of Copernicus’s great circle. Incredulous, Tycho sought alternative means to realize the best of Copernicus’s ideas without moving the Earth, and came up with the compromise that bears his name. In the Tychonic system, Mercury, Venus, Mars, Jupiter, and Saturn all orbit the Sun, while the Sun, in turn, carries them along as it orbits the central, immobile Earth.
