GEORG JOACHIM RHETICUS and Erasmus Reinhold are far from being household names. A few specialists will recognize Rheticus as Copernicus' only disciple and Reinhold as the author of the handy tables that embodied Copernicus' astronomy. But in the mid—sixteenth century, Reinhold was the leading mathematical astronomer in Europe and the astronomy professor at Wittenberg—the hub of the German educational system—while Rheticus was the professor of mathematics there.
Wittenberg—Hamlet's university in Shakespeare's imagination— had opened in 1502 as a sleepy provincial Saxon school that enrolled about forty students a year, but within three decades it had become the seething central pivot of the Lutheran Reformation. In 1517 Martin Luther (who had been teaching at the university since 1508) had posted his ninety-five debating theses on the castle church door in Wittenberg, setting into motion the Protestant religious upheaval. Wittenberg and its university remained Luther's headquarters as he defied both pope and Holy Roman Emperor, while its students and faculty became the reformer's ardent supporters. By 1527 the Lutheran heresy had become German orthodoxy.
Luther's chief educational lieutenant, Philipp Melanchthon, guided the university. His admirers called him Praeceptor Germanis—the teacher of Germany. "I am born to war," Luther wrote, "but Master Philipp walks softly and silently, tills and plants as God has gifted him richly." Melanchthon was enthusiastic about astronomy, and when Wittenberg's longtime astronomy professor died and the mathematics professor transferred to the philosophy faculty, he arranged to appoint two young graduates to the vacant posts.
Reinhold, who got the senior appointment, had come from Saalfeld, a small town midway between Leipzig and Nuremberg. He had enrolled at Wittenberg in 1530 and received his master's degree there several years later. His obvious abilities won him a faculty position almost immediately thereafter. From all accounts he was a steady, well-beloved teacher. In those days the faculty members took their turns at being dean, and Reinhold would serve in that position in 1540 and again in 1549, and for a spell in 1549-50 he was the rector. Even when he wasn't officially dean, he was sometimes asked to write the headings in the official matriculation book because his handwriting was clear and bold.
Meanwhile, Georg Joachim Rheticus had matriculated at Wittenberg in the summer of 1532 along with 130 other young scholars. Few of his classmates made enough of a mark to be listed in Christian Jocher's All-gemeines Gelehrten-Lexicon, a standard source of German Renaissance biographies. But he was bright enough to be noticed by Melanchthon, and in 1536, when he was twenty-two with a fresh master's degree, he was recruited to be the lecturer in "lower mathematics"; in the same year Reinhold became the lecturer in astronomy.
Rheticus was clearly of a different stripe from Reinhold. "Rheticus" was in fact not his original name. Some of his colleagues had taken fancy Greek translations of their names. Schwarzerdt became Melanchthon, though nearly everyone simply called him Philipp. Joachim Camerarius, the humanist leader who eventually persuaded young Rheticus to transfer to Leipzig, was born Kammermeister. "Rheticus," however, was not a translation of a vernacular family name. Young Rheticus was christened Georg Joachim Iserin, but when he was fourteen, his father, a medical doctor, was convicted of swindling and beheaded. The traumatized teenager was obliged to take another name. When he enrolled at Wittenberg, he used his mother's maiden name, de Porris, but soon he became known as Rheticus, an adopted toponym, taken from the Roman province of Rhaetia surrounding what was then and now the southwestern part of Austria.
Though he was a close colleague of Reinhold, who referred to him as "our Joachim," it is not at all clear that they were good friends. Besides being immensely interested in astrology (concerning which Reinhold was rather indifferent), Rheticus became closely affiliated with a group of raucous and iconoclastic young poets. One of them scandalized the community with a vulgar lampoon of the university leaders, including a veiled insinuation that Reinhold's wife was unfaithful. The young man was sent packing, and most of the rest of the group found Wittenberg too uncomfortable for their continued presence. Even Rheticus decided it was time to take a trip, and armed with letters of introduction from Melanchthon, in 1538 he headed south to Nuremberg.
There he met the resident scholar, Johann Schoner, who busied himself with astrology, paper instruments,* and publishing the archive of important astronomical manuscripts left over from the previous century, when Johannes Regiomontanus, the most important astronomer of the 1400s, had lived there. Presumably, Rheticus found out from Schoner† about the new cosmology under development in that "far corner of the Earth" (as Copernicus himself described the northernmost diocese in Poland where he lived and worked). No doubt Schoner told him that the Polish astronomer, who worked as canon at the cathedral in Frauenburg,‡ had some incredible notions about fixing the Sun in the center of a planetary system, and throwing the seemingly solid, immobile Earth into motion. How in the world Schoner knew about Copernicus is anyone's guess. Some have assumed that since by 1514 Copernicus had sent out at least one known copy of his preliminary prospectus for his heliocentric system, the so-called Commentariolus, Schoner probably saw a copy. Or Schoner could have heard the news through the astronomical grapevine that demonstrably connected sixteenth-century astronomers. Witness the case of Reiner Gemma Frisius, a Dutch doctor and mathematician. As early as 1531 Gemma found out about Copernicus from a well-born Pole, Johannes Dantiscus, who had spent some time in the Low Countries and who had then served as Gemma's patron. So somehow the news had got around.
Life's exigencies had prepared Rheticus to be a rebel, and the heliocentric cosmology, so contrary to the deeply rooted beliefs of the day, must have inflamed his imagination. Psychologically wounded by the execution of his father, he was ready to thumb his nose at a conservative society scarcely prepared to entertain such a radical cosmology. Since there were apparently no details to read in Nuremberg about these stimulating novelties, Rheticus resolved to go to the source to find out precisely what Copernicus was proposing. He may well have received encouragement from both Schoner and the Nuremberg printer Johannes Petreius, who had an interest in seeing Copernicus' work published. Thus in 1539 Rheticus set out on the long journey to the shores of the Baltic in northernmost Poland. While there he decided that making a detailed map of that region would be a good idea, so it was fortunate that the young student he had recruited to go with him, Heinrich Zell from Cologne, had some experience in cartography. By what route they traveled, and by what means, is lost in the fog of history.* Did they walk? Or go on horseback? Or on a wagon? Since Rheticus on his journey to Frauenburg took along three handsomely bound large volumes for Copernicus, and probably some of his own books as well as clothes, he presumably had some form of transport. Quite possibly he used the sixteenth-century equivalent of a rental car, buying a horse in Germany and selling it after he arrived in Poland.
Rheticus must have intended a relatively short visit to Frauenburg, little imagining that his sojourn would stretch not just for a few weeks but for several years. Copernicus had had no formal connections with academia since graduate school in Bologna and Padua. He had neither students nor colleagues who could understand the technicalities of what he was doing. Hence the arrival at the Frauenburg cathedral of a young Wittenberg mathematician would no doubt have provided a unique and even exciting opportunity for the aging Copernicus. The Polish astronomer welcomed his visitor, eager to explain the advantages of his new cosmology.
Map of the portion of Europe relevant to Copernicus' life and times.
In retrospect it seems quite remarkable that the sixty-six-year-old Catholic canon at the Frauenburg cathedral—for that was Copernicus' tenured position, which gave him time and support for his astronomical studies—could take on as a long-term guest a twenty-five-year-old teacher from the centrum of Lutheranism. But in those days, before the Catholic conservatives at the Council of Trent had finally hardened the ecclesiastical lines, the Protestant struggle was still viewed as an intra-family quarrel.
For years Copernicus had been writing a treatise on his Sun-centered cosmology, as already promised long before in his Commentariolus, and by then he had a thick manuscript. But he had never had a disciple, someone to whom he could introduce the intricacies of his astronomy. So the two of them began to discuss his hypotheses, as they were called then, really a term closer in meaning to our modern word devices. Copernicus must have told Rheticus about both levels of his hypotheses—the big one being his cosmological arrangement that put the Sun near the middle of a system of planets (including the Earth) wheeling around it, and the secondary, more technical, batch of hypotheses that accounted for the details of planetary motion. As the two men sat together discussing the details of the heliocentric astronomy, the young Wittenberger became increasingly convinced that the world needed to learn what Copernicus had wrought.
Rheticus must have realized that there was no publisher in Poland who could take on a work so extensive and complex. It required a printer with an international outreach to make the publication financially viable. Even Wittenberg, with its busy textbook publishers, was hardly the place for such an enterprise. Maybe this is why Rheticus brought along the three bound volumes as a gift for Copernicus. Three of the five titles included therein had been printed by Petreius.* They gave visible evidence that the Nuremberg printer could handle Copernicus' magnum opus. Whose idea was this? Maybe Johann Schoner in Nuremberg had suggested that such a display could persuade Copernicus to send his manuscript back to Germany, or it might have been Petreius himself. Schoner was well connected with the Petreius shop, dusting off old manuscripts from the Nuremberg archives or producing new works of his own and sending one to press every year or so.
But Copernicus was reluctant to release his book to a printer. Scholars have deduced that he wanted time to incorporate the trigonometric methods of Regiomontanus's Triangles, one of the gift books from Rheticus, into the mathematical section of his treatise. Rheticus had brought along from Schoner some observations of Mercury, which Copernicus needed to upgrade the section on Mercury. And in making changes to some of the parameters in the planetary theory, he had not had time to bring the tables into full agreement with the revised numbers.† The book was still filled with inconsistencies not as yet ironed out. And Copernicus feared it would just be an object of scorn and derision, or would simply become the book nobody read.‡
To be persuasive, Rheticus needed a further strategy. He asked, and gained permission, to publish an introduction to Copernicus' astronomy. The booklet of seventy pages was printed in the spring of 1540 in nearby Gdansk. In the Narratio prima, or "First Report," Rheticus did not shock his readers at the outset with the heliocentric cosmology. He obliged them to work through a number of pages discussing, for example, complex details of "the motion of the Sun" before springing the big surprise: "These phenomena can be explained, as my teacher shows, by a regular motion of the spherical Earth, that is, by having the Sun occupy the center of the universe while the Earth, rather than the Sun, revolves on a great circle." Rheticus then rehearsed the reasons he had found the heliocentric arrangement compelling. He summed up his arguments by declaring, "All these phenomena appear to be linked most nobly together, as by a golden chain; and each of the planets, by its position and order and every inequality of its motion, bears witness that the Earth moves and that we who dwell upon the globe of the Earth, instead of accepting its changes of position, believe that the planets wander in all sorts of motions of their own." He even added an encomium to Prussia, perhaps yet another ploy to soften Copernicus' reluctance, or possibly an attempt to secure the patronage of Duke Albrecht of Prussia.
The Narratio prima was received with such interest that a reprint appeared in Basel the following year; unlike the original printing, it actually displayed Rheticus' name on the title page. Still Copernicus hesitated, and Rheticus lingered. At last, after twenty-eight months in Poland,* Rheticus was entrusted with a copy of Copernicus' manuscript destined for the Petreius press in Nuremberg, and Rheticus undertook the tedious journey home to Saxony.
Having returned to Wittenberg in 1541 with the manuscript in hand, the long overdue Joachim was appointed a full professor, a signal recognition because then there were only four professors (including Reinhold) in the arts faculty. Because the curriculum was still influenced by the medieval quadrivium† —arithmetic, geometry, astronomy, and music theory—it made sense to have two of the professorships in mathematics. Reinhold had become professor of upper mathematics, and thus the astronomy teaching devolved on him. Rheticus became the professor of lower mathematics, that is, arithmetic, geometry, and trigonometry. He arranged for a local press to print the trigonometric part of Derevolutionibus under the title De lateribus et angulis triangulorum (On the Sides and Angles of Triangles), an up-to-date mathematics text since it included what was only the second published table of sines. Its title page clearly designated Copernicus as the author, even though Rheticus himself had greatly expanded the tables.
The title page of Rheticus' Narratio prima (Gdansk, 1540), the firstprinted announcement of Copernicus' heliocentric cosmology.
In addition to his teaching, Rheticus became dean of the arts faculty for the winter semester of 1541-42. Apparently the appointment was more of a bureaucratic chore than an honor, and faculty members rarely served two consecutive terms. Yet even before he had left Frauenburg, he had asked Duke Albrecht in Prussia (an important patron) to petition the elector of Saxony and the University of Wittenberg for another leave of absence, this time to take Copernicus' manuscript to Petreius' shop in Nuremberg and to see it through the press.
Meanwhile, Erasmus Reinhold, the senior astronomy professor who had stayed home, had edited a new, annotated edition of a traditional advanced astronomy textbook entitled The New Theory of the Planets, and Melanchthon, who was the quintessential preface writer, added an erudite section quoting Xenophon, Homer, Virgil, and Plato. But the most interesting front matter came from Reinhold himself, who, in his own preface, mentioned that he knew of "a modern astronomer who is exceptionally skillful, who has raised a lively expectancy in everybody; one hopes that he will restore astronomy." In case there was any doubt, in the second edition some years later Reinhold made the allusion to Copernicus specific.
Reinhold's hint and Rheticus' Narratio prima of 1540 had alerted the community of astronomers and astrologers that something unusual could be expected. Thus the greatest astronomy book of the sixteenth century, indeed, one of the epoch-making science books of all time, came with at least a modicum of warning. Finally, in the spring of 1543, it was ready at Petreius' press in Nuremberg. Its title page read like an optometrist's chart:
NICOLAUS CO
PERNICUS OF TORUN
ABOUT THE REVOLUTIONS OF
the Heavenly Spheres in Six Books
The first 5 percent dealt with the new Sun-centered cosmology, so "pleasing to the mind." The other 95 percent was deadly technical. It included a handbook of plane and spherical astronomy, a lengthy star catalog only slightly updated from the one in Ptolemy's Almagest (the "bible" of geocentric astronomy, composed around A.D. 150), detailed instructions for going from a sparse collection of observations to the parameters of the planetary orbits, and tables for the prediction of planetary positions. As the publisher's blurb, planted squarely in the middle of the title page read, "You have in this recent work, studious reader, the motion of both the fixed stars and the planets restored from ancient as well as recent observations, and outfitted with wonderful new and admirable hypotheses. You also have most expeditious tables from which you can easily compute the positions of the planets for any time. Therefore buy, read, profit." It was surely a text to be studied, but scarcely to be read straight through.
DID ANYBODY read it? This was the question that the historian of science Jerry Ravetz and I asked ourselves one Saturday evening in October 1970. We had rendezvoused in York, the cathedral town in England's largest county; I was en route to Scotland with my family, and he had come over from nearby Leeds, where he taught at the university. Ravetz and I were both friends of Copernicus because we were friends of Poland—he perhaps because he was a socialist who had retreated to England during the McCarthy era, and I felt connected to Poland because of my formative visit with the UNRRA horses twenty-five years earlier. Jerry had spent some time in Poland, where he had produced a provocative monograph entitled Astronomy and Cosmology in the Achievement of Nicolaus Copernicus. When the International Union for the History and Philosophy of Science appointed a committee to plan for the forthcoming Copernican Quinquecentennial in 1973—the five hundredth anniversary of Copernicus' birth—he was a natural choice for the committee; eventually, he became its secretary, steering the committee with consummate sensitivity around issues that still aroused passions, such as whether Copernicus was Polish or German. As a historian of astronomy, I, too, had become a member of the committee, so it was appropriate that we would get together during my family's trip north from Cambridge, where I was spending a sabbatical semester.
With the celebrations coming up in just under three years, our conversation naturally turned to Copernicus and De revolutionibus. It was such a formidably technical book, we reasoned, that few readers could really comprehend it much beyond the opening cosmological chapters. We remembered Arthur Koestler's claim that it was the book nobody read, and, thinking about various modern "great books" programs and its inclusion in the University of Chicago's encyclopedic Great Books of the Western World series, we concluded there must be far more twentieth-century readers than existed in its first decades. We even ticked off the potential sixteenth-century readers who might have made it to the end.
Rheticus and Reinhold headed our list. Andreas Osiander, the Nuremberg theologian and clergyman who finished the proofreading at the press, was necessarily a reader. Then we added Johannes Kepler, the brilliant German astronomer who in 1596 wrote the first unabashedly heliocentric treatise after De revolutionibus itself, and Michael Maestlin, his teacher at the University of Tubingen. Tycho Brahe, the great sixteenth-century Danish observer and builder of instruments, was another obvious choice.
We paused at the name Galileo Galilei. A physicist, he had little taste for the details of celestial mechanics; we figured he might have owned the book, but that it was unlikely he would have read it to the end. (What I was eventually to learn pretty much verified this judgment.)
Another astronomer working in Italy did make the short list, however: Christopher Clavius, the astronomer behind the Gregorian calendar reform, who had specifically mentioned Copernicus in 1581 in the third edition of his introductory astronomy textbook.*
Then we added the first Copernican in England, Thomas Digges, a man who once lived in the same block as William Shakespeare and whose library might have been of use to the playwright when he was researching background material for Hamlet. Since Digges had translated part of Copernicus' cosmology into English, he would surely have been a reader. John Dee, an eccentric Elizabethan wizard who owned the largest private library in England, must surely have at least owned the book, even if he didn't read it all.
But with those nine likely readers we bogged down, and our conversation drifted off to other topics such as the glories of the York cathedral. Then we bid each other farewell, as early the next day my family was headed toward Edinburgh.
In Scotland serendipity took its course. The Royal Observatory in Edinburgh holds a fabulous collection of rare astronomy books formed by the Earl of Crawford late in the nineteenth century. For years these precious books had been mixed on the open shelves with the ordinary astronomy treatises, but at some point before I arrived they had been collected for safekeeping in a couple of enormous steel cupboards. Among these treasures I stumbled upon a first edition of Copernicus' De revolutionibus that was thoroughly annotated from beginning to end.
Such a discovery would probably have meant little to me except for that conversation just two nights earlier about how few readers we thought the book had had in its first years. If it was read so rarely, why was the very next copy I chanced upon so full of evidence of a most perceptive reader, who had marked innumerable errors and who had worked his way through to the very end, even past the obscure material on planetary latitudes that brought up the rear of the four-hundred-page volume?
The Royal Observatory, Edinburgh, the magnificent edifice resulting from the gift to Scotland in 1888 of Lord Crawford's astronomical instruments and library.
Furthermore, there was a fascinating motto penned across the title page (in Latin): "The axiom of astronomy: Celestial motions are circular and uniform or composed of circular and uniform parts" (plate 4b). I would have expected something like, "This crazy book fixes the Sun and throws the Earth into dizzying motion." But no such thing. Here was a reader who ignored the Big Hypothesis, but who was enthusiastic about the secondary ones. The rich annotations verified that interest—hardly anything in the cosmological chapters, but a dense thicket of marginal comments whenever Copernicus grappled with his little epicyclets that allowed him to eliminate what he believed to be one of Ptolemy's most obnoxious devices.*
Erasmus Reinhold's annotations in the heavily technical section of De revolutionibus, folio 91 verso.
Suddenly, inspiration struck. Perhaps this was a copy from one of those nine readers! But no, that would be an unbelievable coincidence, I told myself. There had to be at least a hundred extant copies (as I naively thought then, badly underestimating the number), and that would make the chance of finding a copy from one of those nine readers about one out of ten, or less. That I had just turned up one of those copies seemed a hypothesis too improbable to entertain for long. But whose copy was it?
I searched in vain for an owner's name. The manuscript inscriptions at the beginning and end provided nary a clue. Then I looked more closely at the heavy pigskin binding. Later I would learn that it was a typical example of a blind-stamped binding—"blind" because the impressed designs had no color or gilding. Around the edges were long patterned strips with biblical figures. Below an empty central panel was the date 1543, and above the panel I noticed the initials ER.
I reacted with a shock. Could the initials stand for Erasmus Reinhold, the leading mathematical astronomer in the generation after Copernicus, and one of the astronomers on our short list of annotators? I seized a pencil and paper to make a rubbing of the dim impression and, to my dismay, found not two, but three, initials: ERS. It seemed my hypothesis had just evaporated.
Back in Cambridge it took a few days to sort out the significance of what I had found. I soon discovered that those three initials, ERS, were exactly what was required for Erasmus Reinholdus Salveldiensis, for in the sixteenth century a man's birthplace—in this case Saalfeld—was a part of his formal designation. Furthermore, the blind-stamps on the binding had been recorded and could be attributed to a Saxon binder, quite possibly working in Wittenberg. I started making inquiries to obtain samples of Reinhold's handwriting, specimens that eventually confirmed my original deduction. And I pondered the implications of the finding. If one book displayed such insights as to how a major professor of astronomy passed over the heliocentric cosmology but accepted the epicyclets, what would more copies reveal?
AND SO MY great Copernicus chase began. At first, I poked around Cambridge, Oxford, and London, all rich repositories of Copernican first editions. Oxford and Cambridge provided a special challenge because there were altogether sixty colleges, each with its own library. Cambridge was easy to search because there existed the published "Adams catalog" of sixteenth-century books in the Cambridge libraries; it took several months, however, to discover that it wasn't complete. Trinity College, Isaac Newton's alma mater and the wealthiest college in Cambridge, actually owned three copies of the first edition, whereas the Adams catalog listed only two. It seemed reasonable to the librarian to declare the third one redundant, so that copy hadn't been listed. Eventually, the fellows at Trinity realized that they faced a dilemma. Clearly they didn't need a third copy of the rare Copernicus first edition, but it was so valuable that if it were auctioned at Sotheby's, there would be a furor in the press to the effect that Trinity College was selling off its patrimony. So the fellows quietly gave up any intention of auctioning it.*
The two first editions Trinity always intended to keep turned out to be the most interesting of the seven copies I found in Cambridge. One, originally owned by a Basel bookseller who had collaborated with the printer of the second edition of De revolutionibus, had already found its way to England by 1570. It was heavily and studiously annotated, probably by the Oxford scholar Edward Hindmarsh, who eventually willed his books to Trinity College, Oxford. How the book got from Oxford to Cambridge is a ruefully poignant story. It was bought in a bookshop in 1794 by one Stephen Street, rector of Trayford in Sussex, who penned the following notice inside the front cover of the book: "This may very probably be a copy of the first edition, if it be, it is worth many Guineas. . . . I hope I shall not be taken for a thief, as I bought this volume of Messrs White's House and have pasted their bill of Parcells into it." However, Street's aging father probably thought he was returning his son's copy to its rightful owner when he gave it to Trinity College, Cambridge, instead of Trinity College, Oxford.
Trinity's second copy of the first edition had been acquired in 1843, on the 300th anniversary of the book's publication, as a gift from Richard Sheepshanks, an English astronomer and fellow of Trinity. The volume was clearly censored, something that puzzled me at the time, and it had some early and seemingly minor notes concentrated in the final part of the book, something that perhaps should have puzzled me at the time but did not.
Finding the books in Oxford was a little harder than in Cambridge because there was no published guide. Very quickly, however, I discovered a private index in the Bodleian Library, which led me to the four first editions scattered throughout the college libraries plus one in the Bodleian itself.
Besides Oxford and Cambridge, the opening rounds of my survey included London, where there is an amazing number of libraries. Who would have guessed that "Dr. Williams's Library," rich in theological volumes, would boast a first-edition Copernicus? How I found out about that one I can no longer remember, nor do I recall who told me about the Polish Institute Library, with its partially annotated but almost hopelessly dilapidated copy. The most memorable experience, however, was not examining the first edition in University College, London, but the path to that library.
In my college philosophy class I had heard about the early-nineteenth-century Utilitarian philosopher Jeremy Bentham, but I had never expected to meet him. After he died, in 1832, in accordance with his will, his body was dissected in the presence of his friends, and his skeleton was then decked out in his clothes and seated upright in a glass-enclosed case that could be wheeled into the council room so that he could continue to participate in college affairs. The mummified head was replaced with a wax effigy. And there he sat in the front hallway of University College, his glassy eyes staring straight ahead, a half-amused expression on his waxen face. It was a distinctly memorable encounter, perhaps to make up for the library's lightly browned, eminently forgettable, unannotated first-edition De revolutionibus.
In those early weeks of searching for first-edition copies of Copernicus' book, I could scarcely have imagined the ultimate scope of the search. Then I was merely checking the copies to see how many contained evidence of serious readership, aiming to make a fairly simple list of locations together with brief information concerning the extent of annotations, if any. Of the dozen and a half copies I managed to locate in Cambridge, Oxford, and London, only one was thoroughly annotated, and two others had some marginalia of note. It was already apparent that Reinhold's copy in Edinburgh had been an incredibly lucky starting point, and it seemed that the yield of richly marked up copies would not be high. Perhaps it was true that the book had not many, indeed, hardly any, readers.
* Schoner published an equatorium, a book with movable disks that could be set to determine the positions of planets. Such disks are called volvelles, and these paper instruments were sometimes used as actual calculating devices and sometimes just for pedagogy. For example, beginning in 1538 the introductory astronomy textbook used at Wittenberg, Sacrobosco's Sphere, always included three or four teaching volvelles, and immediately they were copied in the editions published in Venice, Paris, and Antwerp.
† Because Rheticus later dedicated to Schoner his "first account" of the heliocentric system written while visiting the Polish astronomer, we can suppose he learned about Copernicus during his visit to Schoner in Nuremberg.
‡ Now Frombork in northern Poland; I will use the Polish name when referring to modern geography.
* The same is true for Copernicus himself. When he was Rheticus' age, in 1498, he journeyed from Poland to Italy for his graduate studies. We have no record of precisely when he left or arrived on his 900-mile journey to Bologna, or how he traveled.
* The three bound volumes, shown in plate 4, contained five titles. Ptolemy's Greek Almagest (Basel, 1538) was bound alone. Witelo's Greek Optika (Petreius, 1535) was bound with Apianus's lnstrumen-tumprimi mobilis (Petreius, 1534). The Greek edition of Euclid's geometry (Basel, 1533) was bound with Regiomontanus's De triangulis (Petreius, 1533).
† Since Copernicus's original manuscript survives, which is most unusual for a book printed in the Renaissance, it is possible to see that this is the case.
‡ In the preface to his book, Copernicus expressed his reluctance to publish, saying he feared he would be "hissed off the stage" and: "The scorn that I had to fear on account of the newness and absurdity of my opinion almost drove me to abandon a work already undertaken."
* There is recently discovered evidence that Rheticus actually returned briefly to Wittenberg in December 1540 and delivered a short course on Sacrobosco's Sphere. He must have informed Reinhold, Melanchthon, Schoner, and others about Copernicus' book.
† This division of the mathematical arts goes back to Pythagoras in Greek antiquity; in the fourth century A.D. the Roman encyclopedist Martianus Capella laid the foundations for the medieval curriculum based on the seven liberal arts: the introductory tririum (grammar, rhetoric, and logic) and the more advanced quadrivium.
* Although entitled Commentary on the Sphere of Sacrobosco, Clavius' book went so far beyond the small traditional text written in Paris by Sacrobosco around 1215 that it is considered an independent work. Until Clavius' huge expansion, in one edition or another Sacrobosco's Sphere had been the standard introductory astronomy text for more than three centuries.
* Ptolemy's astronomical handbook, or Almagest, is the classical formulation of geocentric astronomy. It is an epoch-making volume because it showed for the first time that the complex appearances of planetary motion could be accounted for by a group of relatively simple mathematical devices. But one of them, the so-called equant, was heavily criticized in the Middle Ages because it appeared to violate the celestial principle of uniform circular motion. More details, including an example of an epicyclet, are found in appendix 1 of this volume.
* Perhaps that was just as well, because there are always unexpected dangers in deaccessioning. An extra copy of Descartes' Geometry, which Trinity had set aside for sale, turned out to have Isaac Newton's critical remarks scattered throughout the margins. The most spectacular example involved not Cambridge, however, but Gottingen University in Germany. The university library had once owned two copies of Newton's Principia, so they decided to sell the dirty one, all marked up by some previous owner. Only after the duplicate was released did someone discover that the critic who messed up the pages was none other than Newton's rival, Gottfried Wilhelm Leibniz. That copy of the Principia is now one of the great treasures of the Bodmeriana Collection in the outskirts of Geneva.