- Ordering the Heavens: Roman Astronomy and Cosmology in the Carolingian Renaissance
Rarely does one come upon a work as original and as significant as Ordering the Heavens. Bruce Eastwood's prizeworthy book is original because it mines a rich body of evidence that, although in plain view of generations of scholars, has never been studied systematically or properly understood. His work is significant because astronomy and cosmology were central topics in the early medieval intellectual worldview and occupied the best minds of the age. Eastwood shows, for the first time, with great precision and acuity how diagrams in manuscripts functioned as means of both interpretation and instruction.
Eastwood's straightforward approach traces how scholars in the age of Charlemagne and his ninth-century successors read and interpreted four Roman texts on astronomy: Macrobius's Commentary on Scipio's Dream, Pliny the Elder's Natural History, Martianus Capella's allegory of the liberal arts (The Marriage of Philology and Mercury), and Calcidius's Commentarius on Plato's Timaeus. Drawing a clear distinction between computus, a keen Carolingian interest focused on calendrical calculations and cycles, and astronomy, the scientific investigation of planetary bodies and their characteristics, Eastwood argues that ninth-century scholars used Roman astronomy to bring order to their understanding of the cosmos, an implicit order they believed derived from divine creation.
The rediscovery of Roman astronomy and the invigoration of Carolingian astronomy beyond the understanding achieved by Bede (d. 735) occurred [End Page 117] in stages beginning in the early decades of the ninth century with the introduction of Macrobius's view of the cosmos, soon followed by details and explanations found in Pliny's encyclopedia. By the 830s, the eighth book of Martianus Capella's allegory, dedicated to astronomy, provided yet more detail and explanation. Beginning in the 840s, Calcidius's commentary opened the lens wide to a broader philosophical outlook of the heavens and introduced geometrical analysis to astronomical studies. Carolingian scholars pored over these texts and left the record of their investigations and pedagogy in marginal notes in an important number of extant ninth-century codices, in commentaries on the Roman authors, and in sketched diagrams. The diagrams, a visual way of thinking and teaching, emerge as the most intriguing and original sources for arriving at the "buried assumptions and understandings" (29) of the Carolingian reception of Roman astronomy. As Carolingian masters invented diagrams to clarify and explain their authors, sometimes they achieved new understanding and sometimes their renderings were not helpful. Eastwood studies both successful and unsuccessful diagrams to guide his readers "into the hidden geometry of Carolingian mindsets" (29). The book's over seventy illustrations from the manuscripts present extraordinary records of ninth-century scholars explaining science in innovative ways.
In four chapters Eastwood introduces his readers to each Roman author's astronomy. In the case of Macrobius, ninth-century readers were drawn to his discussion of the order of the planets surrounding the Earth. The rival Chaldean (Moon-Mercury-Venus-Sun-Mars-Jupiter-Saturn), Egyptian (Moon-Sun-Mercury-Venus-Mars-Jupiter-Saturn), and later Platonist (Moon-Sun-Venus-Mercury-Mars-Jupiter-Saturn) orders presented readers with choices. Macrobius adopted the Platonist order, with Mercury and Venus above the Sun, while Dungal, a ninth-century court astronomer, preferred the Chaldean order he found in Pliny. Thus it happened that copies of Macrobius's text describe his preferred order, while accompanying Carolingian illustrations reflect Dungal's choice, in effect contradicting the text. Carolingian thinkers thought through their texts and dared to challenge them with their own understanding of cosmic order. Macrobius also encouraged speculation about humans who lived below the equator. His influence on Carolingian astronomy was profound, even though the rain diagram his text inspired apparently confused the few masters who tried to render it.
Pliny's Natural History provided useful and specific detail on the precise distances between the planets, the causes and timing of eclipses, the far...