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Possible Influence on Nicolaus Copernicus

Some scholars believe that Nicolaus Copernicus may have been influenced by Middle Eastern astronomers due to uncanny similarities between his work and the uncited work of these Islamic scholars, including Nasir al-Din al-Tusi, Ibn al-Shatir, Muayyad al-Din al-Urdi, and Qutb al-Din al-Shirazi. al-Tusi specifically, the plagiarism in question comes from similarities in the Tusi couple and Copernicus ' geometric method of removing the Equant from mathematical astronomy. Not only do both of the methods match geometrically, however, more importantly they both use the same exact lettering system for each vertex; a detail that seems too preternatural to be happenstance. Moreover, the fact that several other details of his model also mirror other Islamic scholars bolsters the notion that Copernicus' work may not have been only his own.

There is no evidence that any of the direct work of Nasir al-Din al-Tusi ever made it to Copernicus, however there is evidence that the mathematics and theories did make the journey to Europe. There were Jewish scientists and pilgrims who would make the journey from the Middle East to Europe, bringing with them Middle Eastern scientific ideas to share with their Christian counterparts. While acknowledging that this is not direct evidence that Copernicus has access to al-Tusi's work, it does show that it was possible. There was just such a Jewish scholar by the name of Abner of Burgos who wrote a book containing an incomplete version of the Tusi couple that he had learned second hand, which could have been found by Copernicus. It is important to note that his version had no proofs of the geometry either, so if Copernicus had obtained this book he would have had to complete both the proof and mechanism. Additionally, some scholars believe that, if not Jewish thinkers, it could have been transmission from the Islamic school in Maragheh, home to Nasir al-Din al-Tusi's observatory to Muslim Spain. From Spain, al-Tusi and other Islamic cosmological theories could spread through Europe. Spread of Islamic astronomy from Maragheh Observatory into Europe could have also been possible in the form of Greek translations from Gregory Choniades. There is evidence as to the means of Copernicus acquiring the Tusi couple and suspicious similarities, not only in math but in visual details as well.

Despite this circumstantial evidence, there is still no direct proof that Copernicus did plagiarize the work of Nasir al-Din al-Tusi, and if he did that he did so intentionally. The Tusi couple is not a unique principle, and as the equant was a problematic necessity to preserve circular motion it is possible that more than one astronomer wished to improve on it; to that end, some scholars argue it would not be difficult for an astronomer to use Euclid 's own work to derive the Tusi couple on their own, and that Copernicus most likely did this instead of stealing. Before Copernicus ever published the work on his geometrical mechanism, he had written at length his dissatisfaction over Ptolemaic astronomy and the use of the equant, so some scholars then purport that it was not unfounded for Copernicus to have rederived the Tusi couple without having seen it as he had clear motive to do so. Also, some scholars that argue Copernicus did commit plagiarism say that by never claiming it as his own, he inherently condemns himself. However, others critique that mathematicians do not normally claim work like other scientists, so declaring a theorem for oneself is an exception and not the norm. Therefore, there is motive and some explanation as to why and how Copernicus did not plagiarize, despite the evidence against him.