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Zafar Bhatti, Warwick, UK
In the previous instalment of this series, the Doubts (Shukuk) Movement was explored, wherein Muslim scientists challenged the foundational Greek notions the world had clung to for centuries.
Here we turn our sights on the European Renaissance, and how it contributed to the cosmic map we know today. We further examine how Islamic astronomers influenced science to evolve in this direction. From plagiarism to planetary corrections, we take a look at Copernicus and the introduction of heliocentricity.
Our journey to understand the motion of the ‘five wandering stars’ now takes us to the eastern shores of Europe on the 29th of May, 1453. Sultan Mehmet II was leading an army of over 100,000 soldiers, and would finally conquer the ‘impenetrable’ city of Constantinople, the capital of the Eastern Roman Empire. It was a day of historic proportions, which sent shockwaves throughout Europe and history itself. Whereas the Muslims rejoiced, the Christians were inconsolable.
This was a precursor to seismic shifts in the political powers of the world, described in the Holy Qur’an with the words, ‘when the mountains are made to move.’[1] Commenting on this verse, Hazrat Mirza Tahir Ahmad (rh), the Fourth Khalifah of the Ahmadiyya Muslim Community, explains that ‘Mountains in Islamic terminology mean great worldly powers.’ [2] In his book Revelation, Rationality, Knowledge and Truth, His Holiness (rh) further places the timings of the seismic shifts (referred to in this verse) to the 15th century. In fact, the subsequent verses in this chapter, which relate to the widespread publication of books, the joining of seas by canals, the furthering of women’s rights, the development of new modes of transport, and other changes that have occurred since, all followed this political shift.
Despite this victory in Constantinople, history shows that these seismic changes in the world’s political movements would ultimately be in favour of the Christian nations of the West. Soon after in 1492, the last Muslim stronghold in Spain would fall to Ferdinand and Isabella. The same year, Christopher Columbus would set foot in the Americas, setting in motion the rise of the Western European powers and the decline of Islamic power and influence in the world.
Furthermore, it seems that the fall of Constantinople marks the beginning of the transfer of the torch of knowledge from the Islamic World to the European world, potentially providing the initial spark that led to the enlightenment period of the West, and ultimately igniting a revolution in the understanding of the heavens and the enigma known as the ‘wandering stars’.
In the aftermath of the fall of Constantinople, a cardinal by the name of Basilios Bessarion, who was fleeing the new conquerors, had the foresight to see that the conquering of a city was a small prize on offer. The greater prize lay in the treasure of Muslim scientific learning. In the aftermath of the fall, Bessarion would commission two mathematicians, Peuerbach and Regiomontanus, to embark on ‘another crusade.’ [3] This crusade was not one of the sword but one of the pen; specifically, he commissioned them to create a new translation of Ptolemy’s Almagest. Peuerbach would begin this ‘crusade’ and make Regiomontanus pledge that he would continue it after his own death.
Accordingly, Regiomontanus would travel with Bessarion to Rome ‘where he could consult not only Bessarion’s vast collection of classical manuscripts, but also those of Pope Nicholas V, who had acquired many from Constantinople before its fall to the Turks: these manuscripts form the core of the Vatican Library.’[4] Unfortunately, whatever material Regiomontanus perused at the Vatican to produce their work, is now no longer complete and seems to be lost.[5]
What Peuerbach and Regiomontanus produced is known as the Epitome of the Almagest. This would be the key work that Copernicus relied upon and ‘This was the book that Copernicus…followed, even in preference to the Almagest’. [6] First printed in Venice in 1496, it is the ‘finest textbook of Ptolemaic astronomy ever written.’[7]
However, it must be noted that, even though as far as we are aware, neither Peuerbach and Regiomontanus understood Arabic, their works seem to have an extreme reliance on previous Muslim works. On this point, Arthur Beer writes:
‘Anyone familiar with the history of Islamic Astronomy will recognise at once that there is very little in Peuerbach that is not borrowed or directly copied from the Arabic masters, and nothing at all that would entitle us to speak of an independence and freedom from prejudice, such as is considered the characteristic of the spirit of the renaissance.’[8]
Large parts of Regiomontanus’s works are taken from Muslim scientists without attribution as well. For instance, we read:
‘Regiomontanus’s most important work by far was On Triangles (1464), which established trigonometry as a mathematical science. Most of On Triangles was taken without attribution from Jabir ibn Aflah’s Correction of the Almagest, leading Cardano, a century later, to accuse Regiomontanus of plagiarism.’[9] On the other hand, in the interest of transparency, we also read the opposing viewpoint – that Cardano’s claim is unsubstantiated, and Regiomontanus did not plagiarise.[10]
Peuerbach’s book, the Epitome of the Almagest is itself based on The Almagesti Minor, which was ‘one of the most important works of medieval science.’ [11] This book was a combination of the first half of the Almagest and the works of later Muslim writers such as al-Battani, Thabit ibn Qurra, and al-Zarqali. Its authorship is unknown but it was probably written in the 1200s.[12]
There are two propositions in The Epitome of the Almagest that, according to Swerdlow, ‘lead directly to the Heliocentric theory’.[13] In fact, he goes as far as to say ‘While I do not believe that Regiomontanus ever advocated the Heliocentric theory, he was, through these propositions, virtually handing it to any taker.’[14] These two propositions were precisely the same ones proposed by Ali Qushji of Samarqand. The first proposition was of the depiction of both the inner and outer wandering stars with a purely eccentric model. Swerdlow argues that it was based on these eccentric models that Copernicus was able to arrive at the heliocentric model, placing the sun at the centre of the solar system.[15] Currently, we have no evidence of the means of transmission from Ali Qushji to Regiomontanus – however, it is surprising that two men independently, in the same century, paid attention to the second Ptolemaic anomaly and resolved it in the same way. A coincidence, perhaps?
Copernicus
Nicolaus Copernicus was born in the Polish town of Thorn (now Torun) in 1473, the son of a rich family of merchants. His father died in his youth, after which he was taken under the wing of his uncle, a clergyman. He received a high standard of education, studying at a number of universities.
In 1503, after studying Church law at the University of Ferrara in Italy, he returned to Poland as a church administrator. This was an administrative position, and hence left Copernicus with enough free time to devote to astronomy. It must also be pointed out here that Copernicus was not a priest; this was a misconception introduced by Galileo.[16]
In 1530 he completed the treatise ‘De Revolutionibus Orbium Coelestium Libri Vi’ or ‘Six Books Concerning the Revolutions of the Heavenly Orbs’. Although written in 1530, it was published in book form in 1543. Legend goes that Copernicus received the first printed edition of the book on his deathbed.
This book is one of the key texts in the whole history of scientific literature, and is commonly acknowledged to underpin the scientific revolution of the Renaissance and the overhauling of the old Aristotelian worldview of the universe. As such, its importance in the development and renaissance of the West cannot be overstated.
The key theme of Copernicus’s work is the revolutionary idea that the earth and wandering stars orbit the sun, known as heliocentricity. Until this time, the prevalent theory had been that the entire universe revolves around the earth.
This was not the first time that a heliocentric view of the solar system had been proposed.[17] In fact, the Greek Aristarchus, the Muslim Scientist Al-Biruni, and Indian astronomers had all discussed heliocentric theories:
‘In 1030, Abu al Rayhan al-Biruni discussed the Indian Heliocentric theories of Aryabhata, Brahmagupta and Varahamihria in his Ta’rikh al-Hind (Indica in Latin). Biruni stated that the followers of Aryabatha consider the sun to be the centre. In fact, Biruni casually stated that this does not create any mathematical problems’.[18]
However, the point of difference – as far as we are aware – between Copernicus and those who had previously discussed this idea was that, while others had discussed an idea, Copernicus had actually demonstrated the idea mathematically and proposed its validity cosmologically.
‘De revolutionibus orbium coelestium libri vi’ – On the Revolution of the Celestial Spheres
We will now analyse Copernicus’s work, his sources, and whether any influence of Islamic science exists. However, it must be noted that although ‘the “Copernican Revolution” was one of the pivotal intellectual achievements that have shaped our modern place in the cosmos, there is no surprise that readings, commentaries, and translations of Copernicus’s De Revolutionibus continue unabated. What is surprising, almost scandalous, is that none of the translators has ever undertaken a mathematical analysis of the work even approaching Swerdlow and Neugebauer’s opus, before tackling the treacherous task of translating the technical parts of the Copernican treatise.’[19]
Sources
i. Epitome: As has been already discussed, this was the key work that Copernicus relied upon; in fact, he probably did not even refer back to Ptolemy’s Almagest, but rather this work by Peuerbach.
ii. Alphonsine Tables: For his data, Copernicus relied on the Alphonsine Tables. This provided ‘data for computing the position of the Sun, Moon and planets to the fixed stars’. They were compiled on the instruction of King Alfonso X of Castile and were based on the work of earlier Muslim astronomers.
iii. Others: There must have been other texts that Copernicus relied on which we do not know of. As we shall see further below, Copernicus copied large parts of his work from the Maragha Astronomers, indicating his access to their works.
Doubts (Shukuk)
The precursor to any revolution in scientific theory is a critique of the existing models, therefore necessitating the formulation of a new model. As such, Copernicus’s works began with a critique of Ptolemaic astronomy. In particular, his major criticism was regarding the non-uniformity and inconsistency of Ptolemy’s solar system; its different rules for different planets, its epicycles and eccentricities. As such, his stated aim was to remove the complication and construct a simpler and more precise mathematical model.
This critique is nothing more than a summary of the works of the Muslim scholars mentioned previously who, after absorbing Ptolemy’s work, began a systematic critique of its cosmological absurdities. In particular, these doubts are captured in Ibn-al Haytham’s (965-1040) Al-Shukuk ala Batlamyus (Doubts concerning Ptolemy), the dominant intellect of Averroes, and Geber of Spain, with Copernicus calling the latter the ‘egregious calumniator of Ptolemy.’[20]
As such, we clearly see that it was the Muslim Shukuk movement that was the inspiration to Copernicus’s theory.
Plagiarism by Copernicus of Muslim Work
We should recognise that there are two revolutionary features of Copernicus’s work: firstly, the move to the Heliocentric theory, and secondly the removal of the equant and resolution of the first Ptolemaic anomaly. This second part is based entirely on the work of the Maragha astronomers, specifically the models of Ibn al-Shatir. Although people refrain from using the word plagiarism in application to Copernicus, the removal of the equant and resolution of the first Ptolemaic anomaly amounts to direct plagiarism, and I shall detail what we know with regard to this.
‘Copernicus remains far too reticent about acknowledging the sources of his information’, states Swerdlow. [21] For example, ‘he hardly admits the existence of Regiomontanus’, even though constantly relying on the Epitome ‘for numerical parameters, geometrical demonstrations, methods of solving problems, and observational records.’[22]
This seems to be a striking feature of European scientists of that age who ‘as was customary during the Renaissance, [fail] to mention [their] more immediate predecessors’. [23] Some have argued that Copernicus does mention many Arab scientists, quoting Battani no less that twenty-two times; however, as will be shown below, there is no doubt that he also directly plagiarises without attribution.
I speculate that the distinction is that where a work was commonly known, the Renaissance scientist would attribute the appropriate reference, and where a particular item of knowledge was not commonly known, they would appropriate that knowledge as originating with themselves.
We have already seen that Copernicus relies heavily on Regiomontanus’s Epitome, who in turn relies heavily on Islamic advances in the Almagest, both of which were largely unacknowledged. In this regard, the reliance can be so complete that it can be said that Copernicus effectively takes the model made by the Muslim scientists in the previous ages, but instead moves the centre of the universe from the earth to the sun. Recall that from a mathematical point of view, it doesn’t matter which frame is used as a reference; it could equally be the sun or the earth. In this way ‘Copernicus ended up relying…heavily on the works of Ibn al-Shatir when he used, among other things, a lunar model that was identical to that of Ibn al-Shatir, and used the same Tusi Couple, in the same fashion as was done by Ibn al-Shatir, in order to account for the motion of Mercury.’[24]
Lunar Model
A striking find was made by Edward Kennedy in the 1950s. He discovered the works of Ibn al-Shatir (1304-I375/6 CE) in his book Kitab Nihayat al-Sul fi Tashih al-Usul (A Text of Final Inquiry in Amending the Elements). What was striking was that the lunar theory presented in this work ‘except for trivial differences in parameters, is identical with that of Copernicus.’ [25]
Roberts writes that ‘Ptolemy assumed a circular path for the sun, whereas the orbit of Ibn al-Shatir’s sun deviates slightly from circular motion. The major fault of the Ptolemaic lunar model is in its exaggeration of the variation in lunar distance. The major Copernican contribution to the lunar theory lies in the elimination of this Ptolemaic fault.’ [26] And it is this contribution which is identical to that of Ibn al-Shatir.
Mercury Model
In a precursor to the De Revolutionibus called the Commentariolus, Copernicus presents a model which is identical to Ibn al-Shatir’s model of Mercury (not taking into account heliocentricity). Again, the work is taken without attribution, and even more surprising, Copernicus fails to understand its significance:
‘Copernicus apparently does not realise that the model was designed, not to give Mercury a larger orbit (read epicycle) when the Earth (read centre of the epicycle) is 90 degrees from the apsidal line, but to produce the greatest elongations when the Earth (read centre of the epicycle) is +/- 120 degrees from the aphelion (apogee).’ [27]
When Copernicus did write the De Revolutionibus, he had, by that point, understood the significance and made the correct interpretation. However, the central point is that he copied a previous Arab model without attribution, and earlier, without understanding.
Page 422, Copernicus, The Man, the Work, and Its History, Willy Hartner; the figure on the left shows a Tusi Couple found in Nasir al-Din’s Tadkira fi ’ilm al-hay’a. The ‘Arabic letters from top to bottom are A, H, D, B. The point of contact between the two circles is designated G.’ The figure on the right is from Copernicus’s De Revolutionibus and has identical lettering.
Tusi Couple
The Tusi Couple and Muayyad al-Din Al-Urdi’s lemma (used to simplify Ptolemy’s work by explaining away the equant) were used extensively by Copernicus when resolving the motion of the upper planets. Again, they were used without attribution.
Astonishingly in 1973, Willy Hartner discovered that Copernicus’s proof of the Tusi Couple even carried the same ‘alphabetic designators for the essential geometric points’.[28] For example, where aleph was used by Tusi, Copernicus uses ‘A’, where ba is used in the Arabic, ‘B’ is used by Copernicus, and so on.
What this shows us – along with the plagiarism of the Mercury Model without referencing in Commentariolus – is that the works of the past Arab scientists was a crutch of sorts for the early European scientists. They built on the former’s understandings, at times copying directly from the pages of their books without any reference or acknowledgement.
Mechanism of Transmission
The instrument of transmission of Ibn al-Shatir’s model seems to have recently been found ‘thanks to the recent work of Tzvi Langermann and Robert Morrison,’ from whom ‘we now know that a certain Jewish scholar named Moses Galeano brought knowledge of Ibn al-Shatir’s models to the Veneto (and environs such as Padua?) at the time Copernicus was studying in Italy.’[29]
Another avenue of transmission found by Neugebauer’s research identifies a Byzantine Greek manuscript in the Vatican Library known as Gr.211 which was a Greek Version of Tusi’s Couple. [30] Further research will almost certainly unveil more documents in this area.
What Motivated Copernicus to Heliocentricity?
Recall that there were two fundamental anomalies plaguing the Ptolemaic model:
Anomaly One was addressed by the Maragha astronomers, through combining the Urdi Lemma and the Tusi couple by Ibn al-Shatir, to describe the motions of the wandering stars in terms of uniform circular motion.
Anomaly Two, which was addressed (but not fully resolved) by Ali Qushji and Regiomontanus, through the description of the inner and outer wandering planets with an eccentric motion.
So what motivated Copernicus to move to a heliocentric model? If it is simply the removal of the equant points and resolving non-uniform circular motion, then that is achieved by copying the Maragha astronomers. Why go further to a heliocentric model?
This has puzzled researcher after researcher, and the more each researcher adds, the more intriguing it becomes as to why Copernicus – after making one of the most, if not the most, seismic pronouncements ever made in science – himself did not spend more time in detailing how he reached the theory. As he overhauls thousands of years of astronomical thought, he demolishes the Aristotelian view of the world; yet, his silence on how he got there is deafening. I present three plausible reasons as to what may have led Copernicus to a Heliocentric theory. Remember, we are not arguing why heliocentricity is a ‘better’ system that a geocentric one – rather, simply what motivated Copernicus to make the switch.
Epitome of the Almagest
I think the most coherent and authoritative account is by Swerdlow, which was based on the propositions of Regiomontanus in the Epitome (which are the same as those that Ragep states) and were proposed earlier by Ali Qushji under the stewardship of Ulugh Beg. Copernicus’s notes show that he adapted the parameters of his planetary theory from the Alfonsine Tables, first to eccentric models of the superior and inferior planets described by Regiomontanus in the Epitome of the Almagest, then, through simple and direct transformations, to heliocentric models which give the order and distances of the planets from the mean sun [31], the centre of the earth’s sphere. However, there are a number of issues with this account. Primarily, why doesn’t Copernicus detail the same; secondly, why does Copernicus himself state that he set out trying to resolve the problem of the equant (Anomaly One), whereas it seems it was the resolution of the second anomaly that led to his theory of heliocentricity, rather than resolution of the first?
The Maragha Astronomers
The second possible trigger point for the move to heliocentricity is proposed by Ragep and others [32]; that is, the simplification of the Ptolemaic system into an epicyclic model and resolution of the first anomaly was what led us to heliocentricity. To be fair, however, it has not been robustly demonstrated as to what that mechanism was. If not directly (as Ragep states), it could be that the resolution of the first anomaly made the second anomaly clearer and easier to resolve.
As Ptolemy himself states ‘In the case of the research about the anomalies, the fact that there are two anomalies appearing for each of the planets, and that they are unequal in magnitude and in the times of their returns, works a good deal of confusion. For one of the anomalies is seen to have relation to the sun, and the other to the parts of the zodiac, but both are mixed together so it is very hard to determine what belongs to each.’ [33] Although I hasten to add this has not been demonstrated either.
Re-ordering of the Inner Planets
The third proposition is my own, something far simpler but which would require further research. Previously, we read how the Andalusian mathematician Geber repositioned the inner wandering stars (Venus and Mercury) to be outside of the Sun. I propose that this necessarily leads to a physical model which could only be resolved by either a heliocentric or geo-heliocentric model.
In short, questions hang in the air about Copernicus’s derivation of heliocentricity. Copernicus seems to advance the heliocentric theory, ostensibly to resolve non-uniformity in the cosmological model. Yet this had already been achieved by the Maragha Islamic astronomers. He plagiarised, even though he was about to present one of the most groundbreaking discoveries in scientific history. Why plagiarise? He does not even call for the overhaul of Aristotelian physics, as a heliocentric model must necessarily entail. He never reasonably answers the objections against a heliocentric model which were prevalent at the time. Finally, he never himself provides the key motivation to his derivation.
How Copernicus got his information regarding the Maragha astronomers is still not certain, and if he had received that information, he may have received more. As Kesten writes in his book Copernicus & His World, although not referring to Copernicus:
‘Only ignoramuses are proud of their originality or try to wipe out all traces of their own plagiarisms; either they believe they have invented everything themselves or that they have taken everything from others.’ [34]
For me, this is the final question mark that hangs equally over both Regiomontanus and Copernicus; how much did they take from others?
In the next edition, we will cover the works of Brahe, Kepler, Galileo and Newton, all of whom significantly contributed to our understanding of the universe. Did they make isolated discoveries, or did Islamic science contribute to this stage of astronomy?
About the Author: Zafar Bhatti earned a Master’s degree in Physics from Imperial College London and has since gone on to build a career in the IT industry.
ENDNOTES
1. The Holy Qur’an, 81:4.
2. Hazrat Mirza Tahir Ahmad (rh), Revelation, Rationality, Knowledge and Truth (Tilford: Islam International, 1998), 592.
3. Jeff Suzuki, Mathematics in Historical Context (Washington, DC: Mathematical Association of America, 2009), 173.
4. Ibid.
5. Noel M. Swerdlow, The Derivation and First Draft of Copernicus’s Planetary Theory: A Translation of the Commentariolus with Commentary,(American Philosophical Society), 426. Source: Proceedings of the American Philosophical Society, Vol. 117, No. 6, Symposium on Copernicus (Dec. 31, 1973), pp. 423-512.
6. Nicolaus Copernicus, The Derivation and First Draft of Copernicus’s Planetary Theory: A Translation of the Commentariolus with Commentary , ed. Noel Swerdlow, 1971, 5.
7. Ibid.
8. Arthur Beer, Peter Beer, and Willy Hartner, Vistas in Astronomy (Pergamon, 1973), 128.
9. Jeff Suzuki, Mathematics in Historical Context (Washington, DC: Mathematical Association of America, 2009), 174.
10. Ernst Zimmer, Regiomontanus: His Life and Work, trans. Ezra Brown (Amsterdam: Elsevier Science Publishers, 1990), 190.
11. http://www.brepols.net/Pages/ShowProduct.aspx?prod_id=IS-9782503581378-1
12. Noel M. Swerdlow, The Derivation and First Draft of Copernicus’s Planetary Theory: A Translation of the Commentariolus with Commentary, (American Philosophical Society), 425. Source: Proceedings of the American Philosophical Society, Vol. 117, No. 6, Symposium on Copernicus (Dec. 31, 1973), pp. 423-512.
13. Nicolaus Copernicus, The Derivation and First Draft of Copernicus’s Planetary Theory: A Translation of the Commentariolus with Commentary , ed. Noel Swerdlow, 1971, 4.
14. Ibid., p. 47.
15. Ibid.
16. Edward Rosen, “Copernicus Was Not a Priest,” American Philosophical Society 104, no. 6 (1960).
17. Thomas Kuhn, The Copernican Revolution : Planetary Astronomy in the Development of Western Thought (Cambridge, Ma: Harvard University Press, 1970), 42.
18. Nidhal Guessoum, “Copernicus and Ibn Al-Shatir: Does the Copernican Revolution Have Islamic Roots? ,” The Observatory 128(June 2008): 233.
19. N.M. Swerdlow and O. Neugebauer, Mathematical Astronomy in Copernicus’ de Revolutionibus (Springer, 1984), 443.
Journal: Journal for the History of Astronomy, Vol.20, NO.2/61/JUN, P.128, 1989
20. R.P. Lorch, The Astronomy of Jabir Ibn Aflah (1975), 85.
21. Nicolaus Copernicus, The Derivation and First Draft of Copernicus’s Planetary Theory: A Translation of the Commentariolus with Commentary , ed. Noel Swerdlow, 1971, 437.
22. N.M. Swerdlow and O. Neugebauer, Mathematical Astronomy in Copernicus’ de Revolutionibus (Springer, 1984), 437.
23. Thomas S. Kuhn, The Copernican Revolution : Planetary Astronomy in the Development of Western Thought (Cambridge, MA: Harvard University Press, 2003), 144.
24. George Saliba, Islamic Science and the Making of the European Renaissance (Cambridge, Massachusetts; London, England The Mit Press, 2011), 164.
25. Victor Roberts, “The Solar and Lunar Theory of Ibn Ash-Shatir: A Pre-Copernican Copernican Model,” The History of Science Society 48, no. 4 (2011).
26. Ibid.
27. Noel M. Swerdlow, The Derivation and First Draft of Copernicus’s Planetary Theory: A Translation of the Commentariolus with Commentary, (American Philosophical Society), 504. Source: Proceedings of the American Philosophical Society, Vol. 117, No. 6, Symposium on Copernicus (Dec. 31, 1973), pp. 423-512.
28. George Saliba, Islamic Science and the Making of the European Renaissance (MIT Press, 2011), 199.
29. Jamil Ragep, “Ibn Al-Shatir and Copernicus: The Uppsala Notes Revisited,” Journal for the History of Astronomy 47(November 2016).
Galeano,’ Aleph: Historical Studies in Science and Judaism, 7, 2007, pp. 283–318 on pp.
290–6; R. Morrison, ‘A Scholarly Intermediary between the Ottoman Empire and Renaissance Europe,’ Isis, 105(1), 2014, pp. 32–57
30. George Saliba, Islamic Science and the Making of the European Renaissance (MIT Press, 2011), 214.
31. The mean sun refers to the average position of the sun, rather than its actual position
32. Jamil Ragep, “Ibn Al-Shatir and Copernicus: The Uppsala Notes Revisited,” Journal for the History of Astronomy 47(November 2016).
33. (Almagest IX.2)
34. Hermann Kesten, Copernicus and His World (London, England: Roy Publishers, 1945), 246.
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