Reading Copernicus

Christoph Clavius’s commentary on Sacrobosco’s De Sphaera refers to a number of rival cosmologies in sixteenth-century Europe. Of the five he mentions, the most important were undoubtedly his own Ptolemaic system and that of Nicolas Copernicus, 1473-1543, a Polish astronomer whose De revolutionibus orbium was printed at Nuremberg in 1543. Copernicus’s work on the revolution of the orbs presented an entirely new planetary order. In this diagram from Nicholas Mulerius’s 1617 edition of De revolutionibus it is clear that Copernicus switched the positions of the Sun and the Earth: now the Sun stands at the centre of the universe and the earth is regarded as just one of the six planets revolving around it, situated between Venus and Mars.



Copernicus, Astronomia instaurata … opera et studio D. Nicolai Mulerii
(Amsterdam, 1617), p. 21.



This change was revolutionary, in every sense of the word, presenting as it did a challenge to the dominant Aristotelian view – and Copernicus was more than aware of this. He was anxious to ensure that the culmination of his life’s work would be accepted by the Roman Catholic Church of which he was a canon, and he therefore employed a complex humanist strategy of dedication to present his work in a favourable light. He prefaced his work with two documents: the first a letter from Nicholaus Schönburg, Cardinal of Capua, 1472-1537, written on 1 November 1536, a year before the cardinal’s death and seven years before the publication of De revolutionibus. Schönburg, a papal secretary to Pope Clement VII, was a powerful advocate at the Vatican. Alive or dead, his name could conjure up respectability. It is likely that Johann Albrecht Widmanstetter had brought an earlier manuscript work by Copernicus, his Commentariolus, to Schönburg’s attention for the cardinal clearly states the core matter of the Copernican system in his letter:

‘For I had understood that you not only had an outstanding knowledge of the discoveries of the ancient mathematicians, but had also established a new system of the Universe, in which you teach that the Earth moves, that the Sun holds the lowest and therefore the central place in the universe, that the eighth heaven remains motionless and perpetually fixed, that the Moon, situated between the heaven of Mars and of Venus, revolves in the annual circuit round the Sun along with the elements enclosed within its sphere; and that you have fully discussed the whole system of astronomy, and assembled the calculated motions of the wandering stars into tables, to the great admiration of all’.*

Schönburg’s plea for Copernicus to ‘communicate your discovery to enthusiasts and to send me at the first possible opportunity your labours on the sphere of the universe together with the Tables, and anything else you have which is relevant to the same subject’ was a powerful piece of propaganda for Copernicus, For this reason it was placed at the beginning of his text.

As Westman points out (1990), Copernicus’s propaganda drive did not stop there. Immediately following the Schönburg letter he placed a lengthy dedication to Pope Paul III, 1468-1549, in which he appealed to Paul III’s well-known interest in humanism and patronage of learning, the first page of which is visible here.


Illustration of first page of dedication to Paul III
Copernicus, Astronomia instaurata ... 
opera et studio D. Nicolai Mulerii 
(Amsterdam, 1617), 
Dedication to Pope Paul III.

Though carefully couched in the humanist language of modesty it is clear that Copernicus’s dedicatory preface was by no means an apology for his text. Rather he indicates that his work alone has cleared ‘the mist of absurdity’ of previous mathematicians, who ‘use only homocentric circles, others eccentric circles and epicyles’. The reference to homocentric circles here is undoubtedly a reference to the work of Fracastoro who had made a similar patronage appeal to Paul III just five years before. As Granada and Tessicini (2005) have shown, Copernicus’s preface to Paul III was not only a justification of his system but must also be read as a response to Fracastoro’s homocentric system.

Copernicus’s many references to ancient authors, especially Philolaus the Pythagorean who had suggested movement for the Earth ‘in a circle round the heavenly fire’, were not only designed to appeal to the humanist drive to go back to ancient sources, but also functioned as a further level of justification. By pointing to the work of the Pythagoreans Copernicus could absolve himself (and hopefully be absolved by the Pope) from the undesirable charge of presenting a novelty, something new which had no substantiation. The language of his preface to Pope Paul III is startling at times in the strength of his conviction: ‘There may be triflers who though wholly ignorant of mathematics nevertheless abrogate the right to make judgements about it because of some passage in Scripture wrongly twisted to their purpose, and will dare criticise and censure this undertaking of mine’ is strong stuff indeed. He carefully made it clear that he did not include the pope among these detractors, ‘ignorant of mathematics’, but rather left the work to the judgment of ‘your Holiness in particular and of all other learned mathematicians’. The deferential tone of the preface was thus coupled with a confident belief in the certainty of his system, a system he had proved ‘by the clearest demonstrations’. It was, however, somewhat ameliorated by Copernicus’s statement that ‘Mathematics is written for mathematicians’, who, Copernicus had no doubt, would accept his findings and among whom was, of course, that most learned mathematician himself, Pope Paul III.

Ironically it was this final cautious suggestion – that the work was a work for mathematicians – that influenced the reception of De Revolutionibus after Copernicus’s death in 1543. Though Copernicus had formulated his theories many years before (as is evident from the text of his manuscript work the Commentariolus, or small commentary, written before 1514), he had been slow to publish. The catalyst came in 1539 from Germany: a German protestant called Rheticus, 1514-1574, from the University of Wittenberg, then the hub of the reformation, had been attracted to Frauenburg by Copernicus’s reputation. He urged Copernicus to publish and undertook to organize publication of De revolutionibus in Nuremberg. Unfortunately Rheticus, by a combination of circumstances, was forced to hand the task of over-seeing the work through the press to another German protestant, the Lutheran theologian Andreas Osiander, 1498-1552.

Osiander, conscious that the central implications of Copernicus’s system might be un-welcome to both Roman Catholics and Lutherans, sought to downplay Copernicus’s claims. He attached an address ‘To the Reader on the Hypothesis in this work’ which heavily emphasised the hypothetical nature of the work. The tone was definitely defensive. Perhaps luckily for Copernicus he died before he could read Osiander’s preface which, by being placed at the beginning of all subsequent editions, ruined the author’s carefully thought-out strategy.

Osiander’s intervention, unwelcome though it was to purist Copernicans, might well have saved the book from outright condemnation by both Catholics and Protestants. By presenting De revolutionibus as a mathematical construct Osiander and Wittenberg mathematicians drew attention to Copernicus’s tables and data, and away from the more startling cosmographical claims. It was this adumbrated Copernicus that both Lutheran theologians and Jesuit astronomers contemplated. While Rheticus himself may have been appalled at Osiander’s intervention (Gingerich, 1973), the ‘Wittenberg compromise’ of Copernicus which developed with Erasmus Reinhold’s Prutenick Tables (1551), and the Roman Catholic reaction to Copernicus visible in Clavius’s commentary on Sacrobosco, emphasised the acceptable face of Copernican theory and, in the main, politely ignored his central thesis. Full adoption of Copernicanism was therefore slow to develop - indeed, as Feingold relates (1984), official support for Copernicanism in English universities came as late as 1620.

Edward Worth’s copy of Copernicus was the 1617 Amsterdam edition of Nicolaus Mulerius (Nicolas de Muliers, 1564-1630), whose edition quickly became the standard one. Like many astronomers, Mulerius had studied medicine and in 1614 he was appointed to the chair of medicine and mathematics at the new University of Groningen. Apart from his edition of Copernicus he is perhaps best known for his Tabulae Frisicae lunae-solares quadruplices of 1611, astronomical tables based on the work of Ptolemy, Copernicus and Tycho Brahe. This and his edition of Copernicus became standard works. The reason for the success of the latter is clearly apparent in this illustration of the first page where we see Copernicus’s text accompanied by notes by Mulerius.


Illustration of Mulerius p.1
Copernicus, Astronomia instaurata ... 
opera et studio D. Nicolai Mulerii 
(Amsterdam, 1617), p. 1.


Mulerius’s work mirrors Clavius’s commentary on Sacrobosco in so far as both are pedagogical in nature. Mulerius’s edition was the third of the early editions of De revolutionibus but unlike the previous editions (Nuremberg, 1543 and Basle 1566), Mulerius excised printing errors from the text, presenting his readers with a corrected explanatory text. The title that he gave the work, Astronomia instaurata (Renewed astronomy) not only appealed to the humanist agenda but might also be taken to be a reflection on the reception of Copernicus up to 1617. Copernicus, in Mulerius’s view, needed to be re-introduced to his reading public.

What is interesting here is that Mulerius himself was not a Copernican. A strict Dutch Calvinist, he considered himself unable to accept the annual rotation of the earth due to his religious principles. Though he accepted the planetary theory of Martianus Capella which involved heliocentric orbits for the inferior planets of Venus and Mercury, like many other commentators he could not accept the re-positioning of the earth, nor the ultimate corollary of Copernicus’s theory – the expansion of the distance to the fixed stars. His Tabulae Frisicae might have included some of Copernicus’s computations but they were heavily dependent on the tables of Ptolemy. As Vermij (2002) has pointed out, his unpublished text on the planets owed far more to Ptolemy and the Alfonsine Tables than to any Copernican pre-occupations. What attracted Mulerius to Copernicus was not his system but the simplicity of his reinterpretation of some of Ptolemy’s less felicitous mathematical constructs, particularly Copernicus’s rejection of the equant.

The divergent reception of Copernicus in early modern Europe is evident also in two other works in Worth’s Library: Libert Fromondus’s Meteorologicorum libri sex (Oxford, 1639) and Ismael Bullialdus’s De lineis spiralibus novae demonstrationes; Exercitationes geometricae; Astronomiae philolaicae fundamenta explicat per S. Ward (Paris, 1657). As the title page of the first text demonstrates, this was one of a number of works which Edward Worth had inherited from his father, John Worth, 1648-1688, who had been Dean of St Patrick’s Cathedral, Dublin.


Fromondus, Meteorologicorum libri sex (Oxford, 1639), title page.

Libert Froidmont/Fromondus, 1587-1653, was a professor of sacred scriptures at the Catholic University of Louvain. Unlike Mulerius who, though he disagreed with Copernicus was prepared to present his work, albeit within a Mulerian framework, Fromondus was adamantly opposed to Copernicanism. He had not always been so. As Van Nouhuys (1998) points out, as a young lecturer in the arts faculty of Louvain in 1615 Fromondus had produced a jeu d’esprit for Saturnalia in which, if he had not specifically lauded Copernicus’s system, was very much open to its possibilities. By 1629 his views had changed and he engaged in a bitter dispute with the Dutch Copernican Philip vans Lansbergen which he continued with the latter’s son, Jacob. Undoubtedly a central factor in this change of heart was the 1616 papal decree forbidding Catholics to defend Copernicanism, but Fromondus’s stance on the Jansenist controversy, and his staunch defence of his friend Cornelius Jansenius, demonstrates that Fromondus was prepared to go to desperate lengths for a cause in which he believed. As Van Nouhuys (1998) relates, as a result of his championing of Jansenius his own works featured on the Index of Prohibited Books no less than eight times; Fromondus’s rejection of Copernicus was therefore not based on fear but on his understanding of the extent of papal authority. In 1616 the papacy had spoken on the issue of Copernicanism and for Fromondus, in the absence of any contradictory biblical or patristric support for the Copernican system, the matter had been settled. Though his work on the comet of 1618 acknowledged that comets were supra-lunary he rejected the Copernican model and instead favoured the half-way house of Tycho Brahe. His work on meteors and comets was a popular one throughout the seventeenth century. Worth’s edition, printed at Oxford in 1639, formed part of a neo-aristotelian printing drive, sponsored by the Chancellor of the University, William Laud.

The reaction of the French astronomer Ismaël Bullialdus (Boulliau, 1605-1694), was far more positively inclined to Copernicus. Brought up a Calvinist by his parents he had converted to Catholicism at the age of 21 and went on to become a priest. For Bullialdus, however, the 1616 degree, made little difference to his views. Unlike Fromondus, Bullialdus’s 1639 Philolai... Libri V, argued for the supremacy of Copernicus over the Tychonic system. By 1645 he was engaging with at least the first two of Kepler’s planetary laws in his Astronomia Philolaica, Opus Novum (Paris, 1645) and in doing so did much to promulgate them to a wider public. In the same book he put forward his own ‘conical hypothesis’ but this engendered severe criticism from Seth Ward, Savilian Professor of Astronomy at Oxford. The work collected by Worth is Bullialdus’s reply to Seth Ward’s attack, Bullialdus’s De lineis spiralibus novae demonstrationes; Exercitationes geometricae; Astronomiae philolaicae fundamenta explicat per S. Ward (Paris, 1657).


Bullialdus, De lineis spiralibus novae demonstrationes; 
Exercitationes geometricae; 
Astronomiae philolaicae fundamenta explicat per S. Ward 
(Paris, 1657), title page.

As Wilson (2003) relates, Bullialdus’s influence may be seen in the work of a contemporary English astronomer, Vincent Wing, 1619-68, whose Astronomia Britannica was collected by Worth.


Illustration: Portrait of Wing
Wing, Astronomia Britannica (London, 1669), frontispiece.


The portrait of Wing attached as a frontispiece to this work draws attention to the fact that Wing earned his living primarily as a land surveyor. His chief fame rests, however, on his astronomical works. Initially heavily influenced by Tycho Brahe, as is evident in Wing’s almanacs of the 1640s, by the 1650s Wing’s work was wholeheartedly Copernican. This is especially apparent in his Astronomia Britannica printed at London in 1669. Perhaps of all his many works this was his most important, firmly supporting Copernicanism by not only his own observations but those of Brahe, Bullialdus and Pierre Gassendi. His decision to publish in Latin was indicative of his desire to reach a European audience and certainly his work achieved widespread acclaim.

For some at least the proliferation of astronomical systems not only involved academic acclaim but could also be lucrative. The following advertisement for Ptolemaic spheres at James Moxon’s shop in 1696 is flanked on the opposite page with an advertisement for a reprint of his father Joseph Moxon’s book The Use of the Copernican Sphere.


Venterus Mandey and James Moxon, Mechanick-powers (London, 1696?), 2S2v-2S3r.


Moxon senior was a printer and globe maker who later became a member of the Royal Society. Trained in the art of globe making he was anxious to make the most of his skill and therefore catered for all markets. The correct title of his work amply demonstrates this: A Tutor to Astronomie …, or, Use of both the Globes (London, 1696). For the Moxons then, the ability to produce both versions of the cosmos was still a lucrative venture, one which points to a lingering attachment to Ptolemaic astronomy despite the advances in astronomical observation made by Brahe, Kepler, Galileo, and Newton.


Other works by these authors in the Worth Library:

Froidmot/Fromondus, Libertus. Liberti Fromondi... Meterologicorum libri sex (Antwerp, 1627).
Froidmont/Fromondus, Libertus. Liberti Fromondi in Academia Louaniensi S. Th. Doct. Et prof. Ord. Anti-Aristarchus siue Orbis-terrae immobilis. Liber vnicus (Antwerp, 1631).
Froidmont/Fromondus, Libertus. Liberti Fromondi in Academia Louaniensi S. Th. Doct. Et prof. Ord. Labyrinthus siue De compositione continui liber unus: Philosophis mathematicis, theologic vtilis ac iucundus (Antwerp, 1631).

Selected Reading:

*All translations in this section are from Duncan, A. M. (ed.) (1976). Copernicus, On the revolution of the heavenly spheres. Newton Abbot.
Boyer, C. B. (1970) ‘Boulliau, Ismael (b. Loudon, France, 28 September 1605; d. Paris, France, 25 November 1695), mathematics, astronomy’, in C. C. Gillespie (ed.) Dictionary of Scientific Biography II, New York: Charles Scribner and Sons.
Bryden, D. J. (2004). ‘Moxon, Joseph (1627–1691)’, Oxford Dictionary of National Biography, Oxford University Press.
Capp, B. (2004) ‘Wing, Vincent (1619-1668), astronomer, astrologer, and land surveyor’, Oxford Dictionary of National Biography, Oxford University Press.
Feingold, M. (1984). The Mathematicians Apprenticeship. Science, universities and society in England 1560-1640. Cambridge: Cambridge University Press.
Gingerich, O. ‘From Copernicus to Kepler: Heliocentrism as Model and as Reality’, Proceedings of the American Philosophical Society, 117, no. 6. Symposium on Copernicus (Dec 31. 1973), 513-522.
Granada, M.A. and Tessicini, D. (2005). ‘Copernicus and Fracastoro: the dedicatory letters to Pope Paul III, the history of astronomy, and the quest for patronage’, Studies in History and Philosophy of Science 36, 431-476.
Hatch, Robert, ‘Short biography of Boulliau’. Available at: Prof Robert A Hatch Boulliao Biography website. (Accessed 22 October 2009)
Hooykaas, R. (1987). ‘The Aristotelian Background to Copernicus’s Cosmology’, Journal for the History of Astronomy XVIII, 111-116.
Pantin, I. (1999). ‘New Philosophy and Old Prejudices: Aspects of the Reception of Copernicanism in a Divided Europe’, Studies in History and Philosophy of Science 30, no. 2, 237-262.
Vanden Broecke, S. (2004). ‘Astrological reform, Calvinism, and Cartesianism: Copernican astronomy in the Low Countries, 1550-1650’, Studies in History and Philosophy of Science 35, 363-381. This is an essay review of Rienk Vermij’s (2002). The Calvinist Copernicans Amsterdam.
Van Nouhuys, Tabitta (1998). The Age of the Two-Faced Janus. The Comets of 1577 and 1618 and the Decline of the Aristotelian World View in the Netherlands. Leiden: Brill.
Vermij, R. (2002). The Calvinist Copernicans. The reception of the new astronomy in the Dutch Republic, 1575-1750. Amsterdam: Koninklijke Nederlandse Akademie van Wetenschappen. Online version available at
Wilson, C. (2003) ‘Predictive astronomy in the century after Kepler’ in R. Taton and C. Wilson (eds.) Planetary astronomy from the Renaissance to the rise of astrophysics. Part A: Tycho Brahe to Newton. Cambridge: Cambridge University Press. Series: The General History of Astronomy.
Westman, R.S. (1990). ‘Proof, poetics, and patronage: Copernicus’s preface to De revolutionibus’ in D.C. Lindberg, & R.S. Westman (eds.) Reappraisals of the Scientific Revolution. Cambridge: Cambridge University Press.