The Revival of Planetary Astronomy in Carolingian and Post-Carolingian Europe (review)

The argument which unites the 10 articles assembled in the present volume is that it was the study of four classical texts during the ninth, tenth, and eleventh centuries which provided the basis for the revival of planetary astronomy which took place in the ninth century. Those key texts were Pliny the Elder's Naturalis historia, Macrobius's Commentary on Cicero's Somnium Scipionis, Calcidius's Commentary on the first two-thirds of Plato's Timaeus, and Martianus Capella's De nuptiis Philologiae et Mercurii. These texts provided Carolingian scholars with the several different theoretical models for understanding the erratic movements of the five known planets as seen from Earth. These models were somewhat contradictory and this generated much further inquiry and discussion during the ninth century as scholars attempted to reconcile them and to tease out their implications. Much of this work was pursued through the glossing of these texts (usually with extracts from one or more of the others) and especially by devising diagrams to illustrate their contents.

In this way, Bruce Eastwood argues, Carolingian scholars developed a 'rationalised' and 'reasoned', but not entirely compatible, set of models of how the planets might well move around the Earth and each other. Carolingian astronomers attempted, in other words, to comprehend the spatial organisation of the heavens by building models based on ancient texts rather then by recourse to close observation and precise measurement. However, the models these Carolingian astronomers developed weathered the coming in the eleventh century of new observational instruments such as the astrolabe and endured until the Copernican revolution. This at least is the argument which is set out with some force in the introduction and in the first essay, 'Astronomy in Christian Latin Europe, c.500–c.1150'.

The articles that follow do provide strong support for this argument's essential premises. An awkward loose end that often rears its head, however, is the problem of the relationship between this form of astronomy and the development of the science of computus in the Carolingian and post-Carolingian period. The texts and commentaries which have been the focus of Eastwood's research are usually (though not exclusively) transmitted among the 'auxiliary' materials found in computistical materials – that is among the many minor 'satellite' texts, glosses and illustrations that were prefixed, inserted into and appended to core components such as Bede's De temporum ratione and De temporibus. Much recent discussion has focused on the way in which computus manuscripts acquired these auxiliary materials and on the myriad ways in which they were edited and 'improved' over time. This tendency has been variously explained as, for example, a product of the pedagogical need to equip abbots and monastic cantors with a broad sense of the workings of time and nature so that they would be better able to perform the tasks of organising the liturgical calendar and the monastic day and as a product of a powerful impulse towards the integration of scientific and religious knowledge which was renewed and given a new thrust by the so-called Carolingian Renaissance. For his part, though he allows that astronomy and computus were commonly studied together (e.g. VII, p. 17) and that the needs of teachers and students were a major force driving the search for better diagrams and clearer texts (e.g. I, p. 251), Eastwood regards the appearance of astronomical materials among the topics that were taught as part of the 'notably utilitarian discipline' of computus as 'an invasion of a practical ecclesiastical study' by a 'theoretical' and 'secular' element which was foreign to its essential purpose (I, p. 243). Religious concerns do figure in Eastwood's argument, but not within the context of the study of his four classical texts. Rather, he argues that it was the need for data to support 'eschatological, numerological, and astrological prediction' which catalysed...