Constellations as Organisms

Anatomical Descriptions in Ptolemy’s Star Catalogue

Abstract

In this survey paper, we examine the language Ptolemy uses in his star catalogue to describe stars. This catalogue has been extensively studied in terms of the data it contains, but its textual descriptions have been largely avoided by systematic analyses. We focus on ‘anatomical descriptions’ (more than 700 in the catalogue), i.e., textual entries used to identify objects (stars) by relating them to body-parts of imaginary constellation figures. We examine the textual corpus constituted by these descriptions, highlighting the properties of its lexicon, as compared to that of other technical texts in ancient Greece. At the syntactical level, by looking at the functional roles of expressions within descriptions, we attempt to reconstruct a general formula (or a handful of related formulae) to which the great majority of anatomical descriptions conform. Its structural elements provide various types of information to assist identification and recognition. We derive statistical results about the relative frequency and variability of various components of our general formula. We conclude that Ptolemy applies a language that is syntactically formal, in line with both the discursive function and other technical texts of antique geometry, but semantically rich, owing to the anatomical context interplaying with the geometrical one. We show that language use reveals the technical role of constellation figures: rather than being but remnants of cultural garnish or lingering superstition, this system of figures provides the cognitive framework for identifying, recognizing, and memorizing stellar objects.