The Revival of Planetary Astronomy in Carolingian and Post-Carolingian Europe

Bruce S. Eastwood

• Publisher: Taylor & Francis
• Year: 2017
• Print ISBN: 9781138731929
• eBook ISBN: 9781351744188
• Edition: 1
• Topic: History
• Subtopic: World History
• Index: History

This title was first published in 2002: Before the introduction of Greco-Arabic mathematical astronomy in the 12th century, what astronomy was there in the medieval West? While we know of developments in computus, which calculated with solar and lunar cycles to create Christian calendars, and in monastic time-telling by the stars, was anything known of the five planets? Using glosses, commentaries, and diagrams to the early manuscripts of four classical Latin authors - Pliny, Macrobius, Martianus Capella, and Calcidius - Bruce Eastwood provides evidence for the extensive development of the sixth liberal art, astronomy, from the time of Charlemagne forward, with a particular focus on the diagrams used and invented by Carolingian and later scholars. Learning to understand the motions of planets in terms of spatial, or geometrical, arrangement, they mined these Roman writings for astronomical and cosmological doctrines, in the process not only absorbing but also creating models of planetary motions. What they accomplished over three centuries was to establish a basic set of models that showed the reasoned order of the planets in the heavens.

IV
Origins and Contents of the Leiden Planetary Configuration (MS VOSS. Q.79, FOL. 93v), An Artistic Astronomical Schema of the Early Middle Ages

At the conjunction of two major traditions in the history of art and the history of science lies a curious manuscript illustration produced in the Carolingian era, a single page in the Leiden manuscript Vossianus Q.79. In the history of the Calendar of 354 (the Calendar of Filocalus), of which no early exemplar survives, this ninth-century illumination has been used to provide certain links and clues to the appearance of the symbols of the months in that late Roman example of pagan imagery. In the more complex history of Aratus's Phaenomena, the same picture, which exists as an appendage to a manuscript of the Aratea, has been used to establish the appearances of certain planetary and zodiacal figures which do not survive in earlier Aratean manuscripts. Finally, in the controversial history of the early evidences for ideas of sun-centered planetary motion, the Leiden illustration has recently surfaced as a witness to the survival of ancient speculations that the planets Mercury and Venus circle the sun rather than the earth.

Unfortunately no study of the Leiden manuscript illustration (hereafter referred to as LC, the Leiden configuration) has focused directly on that image as an independent object of interest. Having been used as evidence for late ancient calendar illustrations, as evidence for Carolingian artistic capabilities, as evidence for Aratus-manuscript imagery, and as evidence for the continuity of an idea of great astronomical interest (pre-Copernican partial heliocentrism), LC remains in many ways an unknown entity. In the following study I shall attempt a reasonably complete definition of LC by means of (i) dating, (ii) studying the astronomical content, and (iii) providing an improved description and discussion of some of the images in LC.

I. The Dating of LC

LC as a particular manuscript illustration survives in no form earlier than that of the Leiden codex (fig. 1). It has as well three noteworthy later copies, one manuscript and two printings, to which we shall refer later. However, the dating of LC as a design takes us back well before the accepted and satisfying date for the Leiden manuscript version, which is Carolingian and somewhere in the first half of the ninth century.¹ The most important fact to establish, if possible, as a basis for historical discussion of LC is the origin of the conception. When did someone first put together just such an illustration? This question can be answered with reasonable certainty and accuracy, once we realize that LC is a special sort of planetary configuration. That is, it places planets in zodiacal signs according to a configuration representing a real date.²

Taking the planetary positions and going backwards in time from the ninth century, the date of our earliest surviving copy, we find only one plausible date. Using the tables for actual positions as generated by Tuckerman, we come to the year A. D. 579 and within that year the date of 28 March (plus or minus one day). In other words, the only year in which we can find all the planets in such a configuration and which lies within the range of dates suggested by other criteria— astronomical information employed and artistic sources and styles—is A.D. 579. No other year emerges from the tables for the period between the first century and the eleventh. The tabular data from Tuckerman corresponding to LC give the following:³

Planet	Zodiacal Sign in LC	28 March 579	LC positions (Degrees from Aries 0)
Saturn	Aquarius	306	300-330
Jupiter	Gemini	90	60-90
Mars	Scorpio	202 (retrograde)	210-240
Sun	Aries	10	0-30
Venus	Taurus	15	30-60
Mercury	Pisces-Aries	343	0(330-30)
Moon	Libra	190	180-210

The tabular information is given for the point in the year where the LC positions best fit. A reader familiar with such tables will recognize, of course, that the year is found primarily by the configuration of the two outer planets (Jupiter, Saturn), while the other planets complete the determination of the year and give the location within the cycle of the year; the moon is the most dependable body for exact dating within any month indicated by the planetary positions. The moon in opposition gives full confidence to a date at (or very near) a full moon, while the discs for the planets are read to place anywhere in a thirty-degree range (perhaps a sixty-degree range for Mercury, located on the border between two zodiacal signs). Thus we pick the date (28 March) with the moon in opposition which comes closest to the other positions. There are some small inconsistencies, which are explicable. Mars is a bit out of Scorpio. However, Mars is in retrograde motion, which may account for the miscalculation whereby LC places Mars in Scorpio rather than in Libra. Mercury is placed on the border between two zodiacal signs in LC. If this is meant to be an exact position, Mercury is half a sign away on 28 March. If we take the borderline placement of Mercury as an indefinite reading, allowing placement in either Pisces or Aries, then our date is acceptable. Venus is one-half sign out on 28 March. For both Mercury and Venus, however, the sun is an overriding factor. Venus and Mercury calculations are more difficult and therefore more subject to error, while the sun's position must correspond in order to provide an acceptable date. The dependable planets, upon which we can most reasonably determine a date, are Saturn, Jupiter, sun, moon. Given small computational errors for those planetary positions in which errors most commonly occur, we have an acceptable date for our planetary configuration. We should also remember that some variation may be due to the configuration itself, for the planetary discs give us positions only by zodiacal sign, not by degrees. Finally, it should be said that the basis for calculating these positions in 579 would most likely have been Theon's Handy Tables, or a version thereof. Theon's tables, used correctly, would produce results essentially the same as the modern tables used above. The version apparently used in the sixth century was the Latin translation entitled Praeceptum canonis Ptolemaei.⁴ The dating to 28 March 579 is, of course, a dating for the original configuration, not for the copy preserved in LC. Nonetheless, this sixth-century dating will allow us to reopen old questions as well as to initiate new questions regarding the contents of LC. I can also suggest that the original design of LC was composed in Italy, for Cassiodorus referred to the presence of Ptolemaic canones in Italy at the time of writing the Institutiones, after 551, perhaps as late as 560.⁵

II. Astronomy

The astronomical knowledge, both explicit and implicit, in LC appears below in an order intended to account most clearly for all the contents of the design. In outline this knowledge, in the order presented, is the following:

(1) I describe the written texts in LC, their sources, their copies in early printed versions, and the nature of their contents. These texts are epitomes of concrete data about the motions of the planets and more general data about the zodiac. They are drawn almost completely from Pliny and show a distinctly didactic character.

(2) The basic pattern of LC is that of an apsidal diagram, namely, according to medieval readers of Pliny, apogees and perigees of the planets. Essentially, each planetary circle shows only its near (perigee) and far (apogee) points from the earth, not the complete orbit of the planet. The apsidal pattern of LC appears in various forms in extant manuscripts of astronomical excerpts from Pliny. This variety plus LC's pattern suggests an evolution in diagramming planetary apsides in Pliny manuscripts, an evolution from more concrete to more abstract meaning.

(3) The heliocentric pattern for Mercury and Venus, added to the pattern of planetary apsides (including Mercury and Venus), brings in an element ultimately contradictory to the more basic apsidal diagram. This heliocentric pattern almost certainly derives from Martianus Capella and is subordinated diagrammatically to the apsidal arrangement.

(4) A detailed analysis of the placement of the written texts in LC and in its later copies yields more awareness of both the understanding of LC by its copiers and also the likely order of manuscript tradition for the design.

(5) A comparison of the fine points of difference between LC and its supposed tenth-century copy shows a likely divergence in the manuscript tradition between LC and this so-called copy in the tenth century. The finer differences also reveal an apparent loss of understanding or loss of interest in the exact correlation between diagram and written text. We presume this to show a change in attitude towards the purpose of diagrams.

Our study of the intellectual content and implications of LC assumes that all details have some meaning, but all details need not show fully consistent understanding by designers and copyists. Mistakes are possible and to be expected, but still have some meaning. The complete content of LC is a dense series of overlays, each of which I attempt to isolate and explain separately. The content of LC bears witness to the use of information and diagrams primarily from Plinian texts, also from Martianus Capella, in a highly abbreviated and didactic form in the latter half of the sixth century somewhere in the Latin West, perhaps Italy.

1

The astronomical content of LC is many-layered, allowing us to understand something about the order of its construction as well as the information and ideas on which it is based. For the moment we shall ignore the zodiacal signs and figures for the months. Apart from the dating elements, the planetary configuration in LC is grounded primarily in information from Pliny's Natural History, Book 2. An interesting element of LC is the textual material running along the planetary circles. These texts also come from Pliny and might be considered later (ninth-century) additions to LC, were it not for their correspondence with the configuration of the planet...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Acknowledgements
• Introduction
• I Astronomy in Christian Latin Europe, c.500-c. 1150
• II Plinian Astronomy in the Middle Ages and Renaissance
• III Plinian Astronomical Diagrams in the Early Middle Ages
• IV Origins and Contents of the Leiden Planetary Configuration (ms. Voss. Q.79, f. 93v): An Artistic Astronomical Schema of the Early Middle Ages
• V The Astronomy of Macrobius in Carolingian Europe: Dungal's Letter of 811 to Charles the Great
• VI The Astronomies of Pliny, Martianus Capella, and Isidore of Seville in the Carolingian World
• VII Astronomical Images and Planetary Theory in Carolingian Studies of Martianus Capella
• VIII Plato and Circumsolar Planetary Motion in the Middle Ages
• IX Heraclides and Heliocentrism: Texts, Diagrams, and Interpretations
• X Calcidius's Commentary on Plato's Timaeus in Latin Astronomy of the Ninth to Eleventh Centuries
• Addenda and Corrigenda
• Index