Writing in the sky: the late antique astronomical illustrations of MS Harley 647

This paper engages with MS Harley 647 in the British Library, London, a manuscript produced probably at the imperial court in Aachen during the reign of Louis the Pious (814-40 CE), which contains the surviving portion (about four hundred and eighty lines) of Cicero's Latin translation of the Greek poem Phaenomena, written by Aratus of Soli between 275 and 250 BCE. The poem is a description of the night sky based on the earliest celestial globe, manufactured by the astronomer Eudoxus of Cnidus in the first half of the fourth century BCE. The text itself, however, is not the most important element of the manuscript: in fact, its dominant feature are the full-page images of constellations, to which Cicero's text, at the bottom of each page, functions as a caption. This article examines the interaction between words and images in the astronomical illustrations of the manuscript, showing how their scientific content is conveyed to the user (at the same time viewer and reader) through the unity of the verbal and the visual. The long-debated question of the originality of their peculiar layout is also addressed, with conclusive evidence supporting the theory of a late Roman model. Finally, the insertion of the text within the illustrations will be interpreted as an allusion to the idea, presented in the proem of the Phaenomena, that the constellations are God's message 'written' in the sky to help humans in their basic activities, above all agriculture: a key concept in Stoic theology that could also appeal to a Christian audience.