The Origin of the Reciprocation Device in Copernicus: Proclus In and Ṭūsī Out.

It has long been argued whether or not Copernicusʼs astronomical theory was formed under the Arabic influence. In this context, one of the focal points has been a problem of whether or not Copernicus knew the device often called as the Ṭūsī-couple, and if so, when, where and how? We will limit ourselves just to this reciprocation device, and try to scrutinize Copernicusʼs own remarks and relevant arguments with the help of his disciple, Rheticus, in order to shed new light on this matter. Accordingly it is absolutely necessary to think again carefully Copernicusʼs exceptionally explicit allusion to Proclusʼs commentary on Euclid. Careful attention to the texts, both of Proclus and of Copernicus, will lead us to a new look at the moot question. Our conclusion is that the reciprocation device is well understandable in terms of the influence of Proclusʼ commentary tradition upon Copernicus which was probably prompted by Paduan Averroist astronomers, but not in terms of the influence of Marāgha School of astronomy [ABSTRACT FROM AUTHOR]