Firm Content, Fluid Forms: Al-Farghānī’s Elements of Astronomy as a Recasting of Ptolemaic Astronomy

In the 9th century, al-Farghānī composed a work on the elements of astronomy which remained well-known for centuries during the medieval period. Through thirty chapters, he presented Ptolemaic astronomy in a way whose “rearrangement” and “rewording” was praised by medieval readers. Not bearing a particular title, this book spread the popularity of Ptolemy’s ideas by being referred to as a “compendium” and a “summary” of the Almagest in its later reception. In excluding diagrams, tables and mathematical calculations, al-Farghānī delivers a descriptive exposition of Ptolemaic astronomy which claims to be “adequate” and “concise”. The main goal of this paper is to explain the structure of al-Farghānī’s exposition and the overall format of the book. In my explanation, I will provide a textual analysis which situates al-Farghānī’s book in broader trends of medieval Islamic astronomical writing. I also consider the audience of his book, which focuses a pedagogical lens on the Elements of Astronomy. Through this analysis, I explore the interaction between the text, script and context of scholarly writing in the Islamicate world in the 9th century.