From the point of view of the history of the sciences, this is a story not often told. Byzantium tends to be (rather unfairly) left out of mainstream histories of European science which, if they treat of the period between the fifth and twelfth centuries at all, do so only with respect to Islamic science leading up to the "twelfth-century renaissance" in the West. As Magdalino shows, Byzantium is a particularly interesting omission, since it never loses touch with Greek science the way that western Europe does, even if its relationship with Hellenism is complex and sometimes difficult. Even more complex is its relationship with contemporary Islamic science, with which it is in much more direct contact than the medieval West was.
This book moves seamlessly between the worlds of politics, theology, and science, and it is here that astrology shows itself to be such a most judicious choice of subject. On the one hand astrology is sometimes marginalized, sometimes widely and officially accepted in Byzantium, and even sometimes close to the heart of imperial ideology. On the other hand it works in very close contact with developments in theology over the centuries in order to try and carve out a justification for itself in terms acceptable to patriarchs and princes alike. There is also another political and theological subplot at work: astrology as a technique is borrowed from both earlier (non-Christian) Greeks, and passed back and forth to Moslem Abbasids and others, including a range of Christian sects of varying acceptability, and through schools at Edessa and Nisba. In Baghdad we get a especially interesting problem, for we have a political and theological enemy with a tantalizing science, if only some way could be found to Christianize it and perhaps also strip it of its perceived Persian or pagan garb (here astrology's exoticism is a double-edged sword).
Magdalino's focus is specifically on astrology and its relationship to Orthodox Christianity. He traces not so much the spread of astrological techniques or beliefs, as the spread of arguments for and against the validity of astrology in the world of (sometimes shifting) Orthodox dogma. In the early chapters of Magdalino's book, the connection between Byzantine science and the Alexandrian science of late antiquity plays a large role. We see Alexandrian scholars and their students fanning out in the east, settling here and there, being pushed around by various wars and conquests, founding schools, and in general acting as a source of transmission of Greek science to both the Arab and Persian worlds. So also their successors act as a source of transmission of Arabic and Persian science back to Byzantium.
Magdalino looks primarily at authors in and surrounding the imperial court. In an early chapter he uses Stephanus of Alexandria and his relationship with the emperor Heraclius as a touchpoint for an examination of the synthesis of the Byzantine and Alexandrian, a syncretism that blends theologies with astrology, philosophy, and imperial politics to produce the initial basis on which Byzantine astrology would later build. The journey of Stephanus from Alexandria to Byzantium mirrors, at least in rough outline, the journey of astrology out of Alexandria, into and then from Persian, Arabic, and Syrian thinkers. The rather serious attribution questions surrounding works under the name(s) of Stephanus give Mogdalino a chance to look a wide range of Greek works and their interrelations to shed some light on the otherwise rather obscure 7th and 8th centuries. In later chapters Magdalino teases out the rather subtle attitudes to astrology in Michael Psellus and Anna Comnena, who seek to limit what we might call popular superstition without actually challenging the theoretical basis of astrology. Magdalino sees Manuel I Comnenus's position vis vis astrology to be one of essentially reconciliation, mirroring Manuel's political and cultural attitudes (attempts to unite the Eastern and Western churches, for example, or his supposedly lenient attitude to Moslem abjuration). So Manuel sided with astrologers in his reign, who were working to maintain the authority of astrology as a science without at the same time asserting a heretical idea of fatalism. Even opposition to astrology during Manuel's reign is couched in political terms: theologians fearing lay incursion into their spheres of influence, a position that would ultimately lead to Manuel's deathbed "abjuration" of astrology, and the petrifaction of orthodox opinion. We are offered in this book an interestingly politicized astrology, but one that is deliberately portrayed as standing somewhere between religion and science, a position I am always wary of. Perhaps it is more useful to use the apparent ambiguity inherent in astrology to challenge the categorization itself? After all, when writers stretch and re-mould the arguments for and against astrology in terms of contemporary theology, they are offering not just a contribution to astrology, but importantly also a contribution to theology--a point underscored by Balsamon's objections, and delightfully illuminated by one of Magdalino's main themes, where he floats the very interesting and provocative suggestion that different arguments for astrology can be mapped onto positions in various theological debates. Take for example the controversies about the status of icons. Iconoclasts, Magdalino suggests, favoured an interpretation of the stars as signs but not physical causes of events on earth, but simultaneously as signs in which we can see the actions (but not the person) of God. It is precisely this studying-the-creator-through-creation idea that gave astrology its traction in Moslem and Western theology, but orthodox suspicions in Byzantium concerning astrology's association with iconoclasm tied with worries about lay incursions on theological authority would, if Magdalino is correct, be responsible for astrology's eventual marginalization in the Greek world. However we also get some interesting results if try the converse of Magdalino's hypothesis: why should it not also be the case that various positions in astrology pushed their readers into different positions with respect to icons? Part of the reason for the slant in Magdalino's account lies in the sources he examines: they include very few practicing astrologers. Instead we get comments on and explanations of astrology made by philosophers, theologians, emperors. Occasionally a horoscope or an astrologer or two gets mentioned in passing, but they are not examined in serious detail except in their relation to "high-level" debates, and we are left wondering what is happening at the level of actual astrological practice, and at virtually all social levels below that of the imperial court itself. In this respect, the book's title is perhaps misleading. It is not so much about the orthodoxy of astrologers, but about astrology in the eyes of the orthodox. Nevertheless Magdalino's story is a compelling one, and there is much to recommend this excellent book.