ABSTRACT

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.