| De revolutionibus orbium coelestium | |
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Original 1543 Nuremberg edition. |
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| Author(s) | Nicolaus Copernicus |
| Language | Latin |
| Subject(s) | Astronomy |
| Publisher | Johannes Petreius |
| City | Nuremberg |
| Publication date | 1543 |
| Pages | 405 |
De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) is the seminal work on the heliocentric theory of the Renaissance astronomer Nicolaus Copernicus (1473–1543). The book, first printed in 1543 in Nuremberg, Holy Roman Empire of the German Nation, offered an alternative model of the universe to Ptolemy's geocentric system, which had been widely accepted since ancient times.
Contents |
Copernicus initially outlined his system in a short, untitled, anonymous manuscript that he distributed to several friends, referred to as the Commentariolus. A physician's library list dating to 1514 includes a manuscript whose description matches the Commentariolus, so Copernicus must have begun work on his new system by that time.[1] Most historians believe that he wrote the Commentariolus after his return from Italy, possibly only after 1510. At this time, Copernicus anticipated that he could reconcile the motion of the Earth with the perceived motions of the planets easily, with fewer motions than were necessary in the Alfonsine Tables, the version of the Ptolemaic system current at the time.
Observations of Mercury by Bernhard Walther (1430–1504) of Nuremberg, a pupil of Regiomontanus, were made available to Copernicus by Johannes Schöner, 45 observations in total, 14 of them with longitude and latitude. Copernicus used three of them in De revolutionibus, giving only longitudes, and erroneously attributing them to Schöner. Copernicus' values differed slightly from the ones published by Schöner in 1544 in Observationes XXX annorum a I. Regiomontano et B. Walthero Norimbergae habitae, [4°, Norimb. 1544].
Remarkably, a manuscript of De revolutionibus in Copernicus' own hand has survived. After his death, it was given to his pupil, Rheticus, who for publication had only been given a copy without annotations. Via Heidelberg, it ended up in Prague, where it was rediscovered and studied in the 19th century. Close examination of the manuscript, including the different types of paper used, helped scholars construct an approximate timetable for its composition. Apparently Copernicus began by making a few astronomical observations to provide new data to perfect his models. He may have begun writing the book while still engaged in observations. By the 1530s a substantial part of the book was complete, but Copernicus hesitated to publish.
In 1539 Georg Joachim Rheticus, a young mathematician from Wittenberg, arrived in Frauenburg (Frombork) to study with him. Rheticus read Copernicus' manuscript and immediately wrote a non-technical summary of its main theories in the form of an open letter addressed to Schöner, his astrology teacher in Nürnberg; he published this letter as the Narratio Prima in Danzig in 1540. Rheticus' friend and mentor Achilles Gasser published a second edition of the Narratio in Basel in 1541. Due to its friendly reception, Copernicus finally agreed to publication of more of his main work—in 1542, a treatise on trigonometry, which was taken from the second book of the still unpublished De revolutionibus. Rheticus published it in Copernicus' name.
Under strong pressure from Rheticus, and having seen that the first general reception of his work had not been unfavorable, Copernicus finally agreed to give the book to his close friend, Bishop Tiedemann Giese, to be delivered to Rheticus in Wittenberg for printing by Johannes Petreius at Nürnberg (Nuremberg). It was published just before Coperniucus' death, in 1543.
Copernicus' magnum opus was the fruit of decades of labor. It rewrote Ptolemaic theory for a moving Earth, and incorporated over a thousand years of accounts of astronomical observations of varying accuracy. In its standard English edition, the book contains 330 folio pages, 100 pages of tables, and over 20,000 tabulated numbers.
The book is dedicated to Pope Paul III in a preface that argues that mathematics, not physics, should be the basis for understanding and accepting his new theory.
De revolutionibus is divided into six "books" (sections or parts):
Copernicus argued that the universe comprised eight spheres. The outermost consisted of motionless, fixed stars, with the Sun motionless at the center. The known planets revolved about the Sun, each in its own sphere, in the order: Mercury, Venus, Earth, Mars, Jupiter, Saturn. The Moon, however, revolved in its sphere around the Earth. What appeared to be the daily revolution of the Sun and fixed stars around the Earth was actually the Earth's daily rotation on its own axis.
For philosophical reasons, Copernicus clung to the belief that all the orbits of celestial bodies must be perfect circles[2] and to a belief in the unobserved crystalline spheres. This forced Copernicus to retain the Ptolemaic system's complex system of epicycles, to account for the observed deviations from circularity and to square his calculations with observations.
Despite Copernicus' adherence to these aspects of ancient astronomy, his radical shift from a geocentric to a heliocentric cosmology was a serious blow to Aristotle's science—and helped usher in the Scientific Revolution.
Rheticus left Nürnberg to take up his post as professor in Leipzig. The Lutheran preacher Andreas Osiander had taken over the task of supervising the printing and publication. In an effort to reduce the controversial impact of the book, Osiander added his own unsigned letter (titled Ad lectorem de hypothesibu huius operis.) printed in front of Copernicus' preface which was a dedicatory letter to Pope Paul III and which kept the title "Praefatio authoris" (to acknowledge that the unsigned letter was not by the book's author).
Osiander's letter stated that Copernius' system was mathematics intended to aid computation and not an attempt to declare literal truth "...it is the duty of an astronomer to compose the history of the celestial motions through careful and expert study. Then he must conceive and devise the causes of these motions or hypotheses about them. Since he cannot in any way attain to the true causes, he will adopt whatever suppositions enable the motions to be computed correctly... The present author has performed both these duties excellently. For these hypotheses need not be true nor even probable. On the contrary, if they provide a calculus consistent with the observations, that alone is enough. ...For this art, it is quite clear, is completely and absolutely ignorant of the causes of the apparent [movement of the heavens]. And if any causes are devised by the imagination, as indeed very many are, they are not put forward to convince anyone that they are true, but merely to provide a reliable basis for computation. However, since different hypotheses are sometimes offered for one and the same...the astronomer will take as his first choice that hypothesis which is the easiest to grasp. The philosopher will perhaps rather seek the semblance of the truth. But neither of them will understand or state anything certain, unless it has been divinely revealed to him. ...Let no one expect anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart this study a greater fool than when he entered."[3]
As even Osiander's defenders point out, the Ad lectorem "expresses views on the aim and nature of scientific theories at variance with Copernicus' claims for his own theory".[4]
Many view Osiander's letter as a betrayal of science and Copernicus, and an attempt to pass his own thoughts off as those of the book's author. An example of this type of claim can be seen in the Catholic Encyclopedia, which states "Fortunately for him [the dying Copernicus], he could not see what Osiander had done. This reformer, knowing the attitude of Luther and Melanchthon against the heliocentric system...without adding his own name, replaced the preface of Copernicus by another strongly contrasting in spirit with that of Copernicus."[5]
Osiander's interest in astronomy was theological, hoping for "improving the chronology of historical events and thus providing more accurate apocalyptic interpretations of the Bible...[he shared in] the general awareness that the calendar was not in agreement with astronomical movement and therefore, needed to be corrected by devising better models on which to base calculations."[4] In an era before the telescope, Osiander (like most of the era's mathematical astronomers) attempted to bridge the "fundamental incompatibility between Ptolemaic astronomy and Aristotlian physics, and the need to preserve both",[4] by taking an 'instrumentalist' position. Only the handful of "Philosophical purists like the Averroists...demanded physical consistency and thus sought for realist models."[4]
Copernicus was hampered by his insistence on preserving the idea that celestial bodies had to travel in perfect spheres- he "was still attached to classical ideas of circular motion around deferents and epicycles, and spheres."[6] This was particularly troubling concerning the Earth because he "attached the Earth's axis rigidly to a Sun-centered sphere. The unfortunate consequence was that the terrestrial rotation axis then maintained the same inclination with respect to the Sun as the sphere turned, eliminating the seasons."[6] To explain the seasons he had to propose a third motion, "an annual contrary conical sweep of the terrestrial axis".[6] It was not until the Great Comet of 1577 which moved as if there were no spheres to crash through, did the idea come under question. In 1609 Kepler fixed Copernicus' theory by stating that the planets orbit the sun not in circles, but ellipses. Only after Kepler's refinement of Copernicus' theory were the need for deferents and epicycles abolished.
Objecting to the Ad lectorem, Tiedemann Giese urged the Nuremberg city council to issue a correction, but this was not done, and the matter was forgotten. Jan Broscius, a supporter of Copernicus, also despaired of the Ad lectorem, writing "Ptolemy's hypothesis is the earth rests. Copernicus' hypothesis is that the earth is in motion. Can either, therefore, be true?...Indeed, Osiander deceives much with that preface of his. ...Hence, someone may well ask: How is one to know which hypothesis is truer, the Ptolemaic or the Copernican?"[4]
Petreius had sent a copy to Hieronymus Schreiber, an astronomer from Nürnberg who had substituted for Rheticus as professor of mathematics in Wittenberg while Rheticus was in Nürnberg supervising the printing. Schreiber, who died in 1547, left in his copy of the book a note about Osiander's authorship. Via Michael Mästlin, this copy came to Johannes Kepler, who discovered what Osiander had done[7][8] and methodically demonstrated that Osiander had indeed added the foreword.[9] The most knowledgeable astronomers of the time had realized that the foreword was Osiander's doing.
Owen Gingerich[10] gives a slightly different version: Kepler knew of Osiander's authorship since he had read about it in one of Schreiber's annotations in his copy of De Revolutionibus; Maestlin learned of the fact from Kepler. Indeed, Maestlin perused Kepler's book, up to the point of leaving a few annotations in it. However, Maestlin already suspected Osiander, because he had bought his De Revolutionibus from the widow of Philipp Apian; examining his books, he had found a note attributing the introduction to Osiander.
Johannes Praetorius (1537–1616), who learned of Osiander's authorship from Rheticus during a visit to him in Kraków, wrote Osiander's name in the margin of the foreword in his copy of De revolutionibus.
All three early editions of De revolutionibus included Osiander's foreword.
Even before the 1543 publication of De revolutionibus, rumors circulated about its central theses. Martin Luther is quoted as saying in 1539:
People gave ear to an upstart astrologer who strove to show that the earth revolves, not the heavens or the firmament, the sun and the moon.... This fool wishes to reverse the entire science of astronomy; but sacred Scripture tells us [Joshua 10:13] that Joshua commanded the sun to stand still, and not the earth.[11]
When the book was finally published, demand was low, with an initial print run of 400 failing to sell out.[12] Copernicus had made the book extremely technical, unreadable to all but the most advanced astronomers of the day, allowing it to disseminate into their ranks before stirring great controversy.[13] And, like Osiander, contemporary mathematicians and astronomers encouraged its audience to view it as a useful mathematical fiction with no physical reality, thereby somewhat shielding it from accusations of blasphemy.[14]
Very soon, nevertheless, Copernicus' theory was attacked with Scripture and with the common Aristotelian proofs. In 1549 Melanchthon, Luther's principal lieutenant, wrote against Copernicus, pointing to the theory's apparent conflict with Scripture and advocating that "severe measures" be taken to restrain the impiety of Copernicans.[15] The works of Copernicus and Zúñiga—the latter for asserting that De revolutionibus was compatible with Catholic faith—were placed on the Index of Forbidden Books by a decree of the Sacred Congregation of March 5, 1616:
This Holy Congregation has also learned about the spreading and acceptance by many of the false Pythagorean doctrine, altogether contrary to the Holy Scripture, that the earth moves and the sun is motionless, which is also taught by Nicholaus Copernicus' De revolutionibus orbium coelestium and by Diego de Zúñiga's In Job.... Therefore, in order that this opinion may not creep any further to the prejudice of Catholic truth, the Congregation has decided that the books by Nicolaus Copernicus [De revolutionibus] and Diego de Zúñiga [In Job] be suspended until corrected.[16]
De revolutionibus was not formally banned but merely withdrawn from circulation, pending "corrections" that would clarify the theory's status as hypothesis. Nine sentences that represented the heliocentric system as certain were to be omitted or changed. After these corrections were prepared and formally approved in 1620 the reading of the book was permitted.[17] But the book was never reprinted with the changes and was available in Catholic jurisdictions only to suitably qualified scholars, by special request. It remained on the Index until 1758, when Pope Benedict XIV (1740–58) removed the uncorrected book from his revised Index.[18]
A few years after Copernicus' death, Erasmus Reinhold developed the Prutenic Tables ("Prussian Tables"; Latin: Tabulae prutenicae; German: Preußische Tafeln) using Copernicus' methods. The Prutenic Tables, published in 1551, were used as a basis for the calendar reform instituted in 1582 by Pope Gregory XIII. They were also used by sailors and maritime explorers, whose 15th-century predecessors had used Regiomontanus' Table of the Stars.
In the preface[19] to De revolutionibus, Nicolaus Copernicus mocked Lactantius, an early Christian author (ca. 240 – ca. 320):
Perhaps there will be babblers who claim to be judges of astronomy although completely ignorant of the subject and, badly distorting some passage of Scripture to their purpose, will dare to find fault with my undertaking and censure it. I disregard them even to the extent of despising their criticism as unfounded. For it is not unknown that Lactantius, otherwise an illustrious writer but hardly an astronomer, speaks quite childishly about the earth's shape, when he mocks those who declared that the earth has the form of a globe. Hence scholars need not be surprised if any such persons will likewise ridicule me. Astronomy is written for astronomers.[20]
A German TV documentary on "The seven greatest lies in history"[21] states that medieval scholars knew full well that the Earth was a sphere. Copernicus is blamed for having omitted to say that Lactantius had been the exception rather than the rule, and thus for having contributed to the flat-Earth myth.
Historians long believed that, at its first publication, De revolutionibus had not been widely read. Owen Gingerich, a widely recognized authority on both Nicolaus Copernicus and Johannes Kepler, disproved this after a 35-year project to examine every surviving copy of the first two editions. Gingerich showed that nearly all the leading mathematicians and astronomers of the time owned and read the book; however, his analysis of the marginalia shows that they almost all ignored the cosmology at the beginning of the book and were only interested in Copernicus' new equant-free models of planetary motion in the later chapters. Also, Nicolaus Reimers in 1587 translated the book into German.
Gingerich's efforts and conclusions are recounted in The Book Nobody Read, published in 2004 by Walker & Co. The research behind this book earned its author the Polish government's Order of Merit in 1981. Due largely to Gingerich's scholarship, De revolutionibus has been researched and catalogued better than any other first-edition historic text except for the original Gutenberg Bible.[22]
English translations of De revolutionibus have included: