Degree Date



Doctor of Philosophy (PhD)


History of Art


Images of the Ptolemaic cosmos were produced in all three major early medieval successors to the Roman Empire (the Carolingian, the Byzantine, and the Umayyad states). Early medieval cosmological images remained formally and iconographically close to their late antique models. They thus provide a point of comparison allowing examination of the changing functions of images. Two primary functions of ancient cosmological images are identified: the epistemological (images as carriers of information about the Ptolemaic world system) and the symbolic (images as signs of “the cosmos”within broader signifying systems).

In early medieval Byzantine art the epistemological function predominated. The Vatican Ptolemy (Vaticanus Graecus 1291), a manuscript produced ca. 750, was a manual intended to ensure imperial access to natural-scientific knowledge. It may thus be compared to contemporary metrological monuments, in particular the Horologion of Hagia Sophia and the Anemodoulion, erected by emperors in Constantinople. Its apparent lack of progeny is related to a jealous “economy of knowledge” that developed from social antagonisms between centralizing emperors and elites determined to maintain independent sources of power.

Charlemagne‟s silver table and the Cathedra Petri have traditionally been considered props for staging the Carolingian ruler as a cosmocrator through use of cosmological imagery. However, in the Carolingian world, as in the Byzantine, the epistemological function of cosmological imagery predominated. The proliferation of manuscripts with cosmological imagery, particularly in the period between ca. 800 and 820, provides a contrast to Byzantine scarcity, and evidence for a porous “economy of knowledge.” Cosmological images aided in the formation of identities shared between state functionaries and hereditary elites.

Cosmographic imagery, both terrestrial (the mosaics of the Umayyad Mosque of Damascus) and celestial (the frescoes of Qusayr „Amra) played a major role in the staging of Umayyad rule. Thus in the early Islamic state it was the symbolic function that predominated. This is related to the gulf between the Umayyad state and its host society, and the necessity for Umayyad caliphs to develop a flexible visual


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