Byzantine Astrology during the Reign of Manuel I Komnenos
Posted by Darin Hayton on 10/10 at 10:33 PM
Anne-Laurence Caudano’s talk on Byzantine astrology—“Controversies and scientific activities of the Byzantine clergy in the reign of Manuel I Komnenos (1143‐1180)—surveyed two letters that, she claimed, reveal the ways astronomy was purged of astrological influence and how, more broadly, science had to conform to orthodoxy.
She opened by summarizing Manuel I’s defense of astrology. His defense rested on three pillars: proper astrology could be distinguished from demonic magic, the stars were not efficient causes, Biblical examples and quotations from Church fathers who did not condemn astrology. Manuel I’s defense was, according to Caudano, simple and easily refuted. He had, for example, misused or misquoted most of his Biblical and patristic sources. Caudano then turned to her two main sources: a letter by Michael Glycas attacking the emperor’s defense of astrology and a second letter by a Peter the Philosopher that defends astronomy and a form of natural astrology.
In his letter Glycas correctly quoted all the patristic material Manuel I had used, showing where it did not support astrology. Glycas further quoted extensively from additional patristic sources that attacked astrology. While showing a familiarity with Ptolemy, he rejected Manuel I’s argument. He, apparently, endorsed astronomy but rejected all forms of astrology.
Peter the Philosopher—about whom we apparently know very little—wrote a “confused and emotional” letter in which he claimed the stars could be used as signs, especially in medicine, but were not causes for events on earth. “Medicine is an orthodox use of astrology.” Again, he distinguished astronomy from astrology, covering a number of “astronomical themes” while rejecting astrological topics. Peter was, however, a “bad scientist,” e.g., he incorrectly noted that the Dog Star rose on 11 July rather than 19 July as reported in other sources. Further, his work drew on a “bad” version of the quadrivium.
According to Caudano, these two letters are properly understood as responses to Manuel I’s defense and show us how scholars at the time were trying separate astronomy from astrology, how they were trying to establish the boundaries for the study of the stars, and finally how science needed to be orthodox.
Caudano’s paper raises some questions. First, how are the terms astrology and astronomy being used by Manuel I, Glycas, and Peter? Given her conclusions, it would have been nice to see Caudano spend some time analyzing the texts themselves for how the authors were using these terms, terms that are fraught with difficulty and ambiguity. Indeed, her entire paper could have traced the ways that these terms were used. Glycas himself wrote another letter in which he discussed the two terms: “Εἰ χρὴ μαθηματικὴν ἐπιστὴμην ἀποτρόπαιον ἡγεῖσθαι παντάπασιν.”1 The letter opens by pointing out that the two types of mathematical knowledge are divided into astronomy and astrology.2 Another set of questions focus on why and to whom these letters were written. In what context should we read these letters? Manuel I’s letter is expressly written to defend astrology against the charges of sacrilege leveled by a “certain monk of the imperial Pantokrator monastery.” Who was this monk and why does Manuel feel obliged to defend astrology? Glycas’s letter is an explicit response to Manuel I’s, but for what reason and for whose benefit? In both cases, it would be nice to know something about the intended recipients of these letters? Manuel I is known to have supported astrology. Who else might have been at court writing astrological texts for the emperor? What was Glycas’s relationship with the court and any other astrologers? John Kammeteros wrote a couple astrological tracts for Manuel I, what was his relationship to Glycas, if any?3 Is Glycas’s letter really a rejection of astrology or is it a refutation of Manuel I’s defense of astrology? Glycas certainly had reason to dislike the emperor, who had had Glycas imprisoned and partially blinded. Then there are the numerous questions about this Peter the Philosopher. Apparently we know little about him beyond a letter and his short treatise on astronomy.
Like many Byzantinists, Caudano is clearly very learned and linguistically talented. Her approach to these letters, however, reflects a historiography that doesn’t hold the authority it once did. In many ways her talk was something akin to intellectual history in which certain terms—astrology, astronomy, science, orthodoxy—represent timeless entities. Rather than try to understand how the historical actors might be using these terms, and why, she seemed to assume that they were unproblematic, and oddly modern. The texts themselves are extracted from the contexts in which they were meaningful. Finally, by abstracting the sources from their contexts Caudano drew sweeping generalizations that, in the final analysis, the source material can’t support. This historiographical difference ensures that the history of Byzantine science remains marginalized within the broader history of science discipline.
1Glycas’s letter is printed in the CCAG, immediately after the letter Caudano sites: M. Glycas, “Εἰ χρὴ μαθηματικὴν ἐπιστὴμην ἀποτρόπαιον ἡγεῖσθαι παντάπασιν,” CCAG V.1, pp. 140–41.⇑
2I’ve only just skimmed the letter, but it looks really rich. The opening line is “Τὰ τῆς μαθηματικῆς ἐπισήμης εἰς δύο ταῦτα, θεοείκελε ἀνήρ, ἀστρονομίαν τε καὶ ἀστρολογίαν διῄρηται….” Glycas, “Εἰ χρὴ μαθηματικὴν ἐπιστὴμην ἀποτρόπαιον ἡγεῖσθαι παντάπασιν,” CCAG V.1, p. 141.⇑
3See H. Hunger, Die Hochsprachliche Profane Literatur Der Byzantiner, pp. 242–43.⇑