The Long Legacy of Ptolemy

Abstract

In 2012 the Union of German Academies of Sciences and Humanities announced the funding of a 25-year Academy Project of research into the reception and study of medieval Arabic and Latin versions of Ptolemaic works. Known as Ptolemaeus Arabus et Latinus (PAL), its primary aim is “to make the Ptolemaic corpus on the science of the stars available to researchers” (p. 3). To achieve this simply stated goal the organizers have created what is probably the largest collaborative, current project in the history of astronomy. Interested scholars may follow the activities of PAL on its website: https:// ptolemaeusbadwe.de. This volume represents results of the first triennial PAL conference, offering a deliberately broad coverage of Ptolemaic astronomy and astrology in Latin, Arabic and Greek. After a useful overview of each of its fourteen contributions, the book begins with four papers on the Greek and Near Eastern Traditions. In his lead-in paper, “The Ancient Ptolemy,” Alexander Jones seeks to present Ptolemy “in the round” and begins by asking which “Ptolemaic” works Ptolemy wrote. Reviewing the evidence on the doubtful works, he exploits the searchability of the digital Thesaurus Linguae Graecae (TLG) to identify traits of Ptolemy’s writing that allow a secure test of his authorship. One result of this is a strong argument for accepting the previously doubtful philosophical work, Criterion, as a work of Ptolemy. After considering the relative order in which Ptolemy composed his works, Jones presents two views of the Ptolemaic canon: a view by discipline and another by prevailing themes. For example, both the Almagest and the Harmonics, although in different disciplines, are “deeply concerned with applying sense perception . . .and reason” to create models underlying observed phenomena (p. 28). Jones concludes by emphasizing Ptolemy’s concern with “mathematically defined modes of representation of the cosmos” (p. 29). To Jones’s examples one might add the Analemma, the subject of Nathan Sidoli’s “Mathematical Methods in Ptolemy’s Analemma.” The analemma was an ancient method of geometrically representing a sphere on a plane, a problem Ptolemy faced in his Planispherium and Geography. Sidoli carefully explains the method, based on the division of the celestial sphere into eight octants by three mutually perpendicular great circles all passing through the observer’s position at the center of that sphere. These three 1081975 JHA0010.1177/00218286221081975Journal for the History of AstronomyEssay Review Essay Review2022