BRUCE S. EASTWOOD

CALCIDIUS'S COMMENTARY ON PLATO'S TIMAEUS IN LATIN ASTRONOMY OF THE NINTH TO ELEVENTH CENTURIES

Prior to the twelfth-century recovery of Greek and discovery of Arabic astronomical (and astrological) texts, the character of European astronomy derived from three traditions: computus, classical texts, and observation (including instruments). By the ninth century each of these was involved with the others, producing an increasing variety of ideas and investigations. While the computistical and observational traditions combined in certain ways to bring about more practical and mathematical understanding of solar, lunar, and occasionally stellar motions, generally in the context of reckoning time intervals, the classical tradition led scholars to expand their frameworks for understanding the order and regularity of the heavens created by God.1 More speculative or theoretical and quite unmathematical in nature, the classical Latin materials that offered astronomical information and doctrines tested the wits of early medieval investigators in quite different ways than did the problems of the other traditions. Among these Roman astronomical works—the writings of Aratus (in translation), Pliny the Elder, Calcidius, Macrobius, and Martianus Capella were predominant—the translation of and commentary upon Plato's Timaeus by Calcidius has received the least attention by modern students of early medieval astronomy. Yet the work of Calcidius, especially his commentary, offers us a revealing field for the display of bold exploration, limits of comprehension, and successful innovation in medieval astronomical study more than half a century before the influx of Greco-Arabic works from ca. 1100 onward. Here I present examples of the boldness, the limits, and the successes from three manuscripts of Calcidius from the ninth to early eleventh centuries.

1 A recent book by S. McCluskey, Astronomies and Cultures in Early Medieval Europe, Cambridge 1998, argues that the essence of early medieval astronomy was the problem- oriented and practical traditions of observational and computistical astronomy. While successful in presenting the content of those traditions, it does not properly explain the place of Roman classical astronomical materials in early medieval astronomy. The present study is an example of what McCluskey's book fails to understand. 172 BRUCE S. EASTWOOD

1. A ninth-century scholar's astronomical compendium

The history of Platonism in the Middle Ages has long held an important position in medieval intellectual history with its focus upon Plato's Timaeus and medieval studies and uses of that text. An important study by Margaret Gibson pointed to the eleventh century as the beginning of intelligent work upon the Timaeus, referring to the earlier, ninth and tenth centuries as a time when it 'seems to have been a venerated curiosity rather than a work that men used and understood. No commentary on the Timaeus has survived from this period; nor any good evidence of independent criticism'.2 More recently Rosamond McKitterick has shown the limitations of such a view in a thoughtful survey of the Timaeus in the scriptoria and libraries of the ninth century, concluding, 'Plato's work seems to have been part of the corpus of works recognized by the early Carolingians as concerning crucial knowledge'.3 For Gibson the commentary by Calcidius was not a topic of concern at all, whereas McKitterick made some references to it and its diagrams. But as a subject of major, even primary, interest among early medieval readers the commentary by Calcidius has aroused no modern attention or study. Yet it was precisely the commentary which was more explicit, more elaborate, and more accessible in its treatment of certain chosen topics from the history of late ancient Platonism. Among these, astronomy is clearly a prime example. Calcidius's commentary provided, often with labeled diagrams, a useful, qualitative introduction to Hellenistic models for stellar and planetary motions along with comment upon their relevance to Plato's doctrines of cosmic and astronomical order. The availability of Calcidius's translation and commentary in the Carolingian world would seem at first glance to have been spare. Only three manuscripts of Calcidius's translation with his commentary survive from the ninth century, and from the tenth century there are again only three copies of the complete work.4 As McKitterick has shown, however, the history of the

2 M. Gibson, 'The Study of the Timaeus in the Eleventh and Twelfth Centuries', Pensamiento. Revista de investigation y information fil os ófica 25 (1969), 183-194, at 184. She repeated and emphasized this view in 'The Continuity of Learning circa 850-circa 1050', Viator 6 (1975) 1-13, at 12, where she labeled it along with Macrobius 'still exotica in the later ninth century'. 3 R. McKitterick, 'Knowledge of Plato's Timaeus in the Ninth Century: the Implications of Valenciennes, Bibliothèque Municipale MS 293', From Athens to Chartres: Neoplatonism and Medieval Thought. Studies in Honour of Edouard Jeauneau, ed. H. Westra, Leiden 1992, 85-95, at 95. 4 McKitterick, 'Knowledge of Plato', 89-90, gives the three ninth-century mss. From the tenth century there remain the mss. labeled as Ba, Brl, and CI by J. Waszink in his edition of Plato Latinus, IV: Timaeus a Calcidio translatus commentarioque instructus, London 1962/1975, cix-cx; the date of Ba has been revised. In addition to these copies there survives from each of these centuries one copy of Calcidius's translation alone. From the late ninth