Science in Context

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[Tdotu]usi and Copernicus: The Earth's Motion in Context 1

F. Jamil  Ragep a1
a1 University of Oklahoma


A passage in Copernicus's De Revolutionibus regarding the rotation of the Earth provides evidence that he was aware, whether directly or indirectly, of an Islamic tradition dealing with this problem that goes back to Na[sdotu]ir al-Din al-[Tdotu]usi (1201–1274). The most striking similarity is the use of comets by both astronomers to discredit Ptolemy's “proofs” in the Almagest that depended upon observational evidence. The manner in which this question was dealt with by Copernicus, as an astronomical rather than natural philosophical matter, also argues for his being within the tradition of late medieval Islamic astronomy, more so than that of medieval Latin scholasticism. This of course is bolstered by his use of non-Ptolemaic models, such as the [Tdotu]usi couple, that have a long history in Islam but virtually none in medieval Europe. Finally, al-Qushji, who was in Istanbul just before Copernicus was born, entertained the possibility of the Earth's rotation; this also opens up the possibility of non-textual transmission.


1 I wish to thank Steven Livesey, Sally Ragep, A. I. Sabra, and Julio Samsó for helpful suggestions. It should be noted that several of the texts discussed in this article are only available in manuscript and have yet to be edited or translated. This will, I hope, be rectified in a forthcoming publication.