A recent textbook on my bookshelf offers a familiar litany of causes of the Protestant Reformation: political motivations, social and economic tensions, and the new medium of print. To these factors must now be added the abundance of astrological writings in the hands of German townsfolk. This is the point made persuasively and emphatically in Robin Barnes's sparkling new book, which demonstrates clearly the close ties between the astrological mindset and the German Lutheran movement. To be sure, Barnes is not the first to have noted the efflorescence of astrology in sixteenth-century Germany or to have linked the astrologers’ prognostications to the evangelical cause. But what Barnes brings to the table is not just a synthesis of the writings of generations of scholars, but rather a fresh and compelling analysis of literally hundreds of annual prognostications (practicas), astrological calendars and other writings on the stars. German burghers took these publications seriously, he argues, and so should we.

Barnes's initial chapters establish the uniqueness of the German case in the decades before 1517. As chapter i demonstrates, cities and towns in the empire were saturated with vernacular astrological calendars, annual practica and other prognostications in a way unmatched elsewhere in Europe. In chapter ii, perhaps the book's most speculative, Barnes argues that immersion in this pervasive astrological culture helped to prepare for the acceptance of the evangelical message by German burghers by inculcating a new view of time, space and the sacred that presented the heavens as a direct expression of God's will, by-passing any intermediaries, and by fostering a sense of apocalyptic expectancy.

Barnes's third chapter covers familiar ground: the numerous prognostications centring on the conjunctions of 1524, with their attendant fear of an apocalyptic Sintflut. Barnes builds significantly upon the work of previous scholars by categorising German flood writings from 1521 to 1524 into three general orientations: humanist astrology, evangelical astrology and evangelical Biblicism.Footnote ¹ While humanist astrologers tended to present a more hopeful scenario, in which a time of renewal would follow a series of tribulations, evangelicals (whether astrologers or biblicists suspicious of the art) used the fear of a great flood to urge repentance, abandoning any hopes for a reform of the Catholic Church.

In his fourth through sixth chapters, Barnes focuses on the growing connection between the Lutheran movement and an astrological world view. In chapter iv Philipp Melanchthon's Wittenberg emerges as the epicentre of an evangelical programme of instruction that deployed a ‘purified’ astrology as a weapon against superstition and as ‘the natural ally of a purified gospel’ (p. 132). Central to Barnes's argument here is a re-reading of Luther's own stance towards astrology: he sees the reformer's attitude towards the science less as one of total dismissal and more as ‘a mixture of disinclination, ridicule, and bemused tolerance’ (p. 134) and Wittenberg students not as torn between the teachings of Luther and Melanchthon but, rather, as fundamentally believing in the complementarity of the book of nature and the book of Scripture.

As Barnes's fifth chapter makes clear, by the mid-sixteenth century astrology was central to a confessionalised Lutheran world view, a fact noted with derision by Catholic observers. In German lands, large numbers of astrologer-preachers helped to integrate astrology with Lutheran teachings in ways that contrasted sharply with the experience of other Protestant confessions, as well as with that of their Catholic counterparts. And despite the reservations of some Lutheran authors, numbers of astrological publications soared in German evangelical towns in the last decades of the sixteenth century.

In chapter vi, Barnes traces a growing pessimistic tone amongst German astrological writers in the second half of the sixteenth century, mirroring the despair and pessimism often remarked amongst evangelical preachers of the time. Astrologers often linked their increasingly apocalyptic prognostications to the sinful state of the German people, invoking the biblical example of the Ninevites to urge their readers to a repentance that might turn aside their dire fate. Barnes persuasively links their ‘astrologically based repentance sermons’ (p. 243) to the project of social control and the conservative political orientation often noted as a feature of Lutheran culture in the late sixteenth century.

Barnes's final chapter examines the disintegration of the tight linkage between astrology and German evangelicals, as seventeenth-century calendar men found themselves torn between a push for a purified, more accurate mathematical astrology; the attractions of Paracelsianism, Neoplatonism, pansophism and Rosicrucianism to counter the prevailing pessimistic emphasis on human helplessness; and a ‘tidal shift’ (p. 291) in Lutheran universities away from Melanchthon's teachings. Theologians now stressed that Scripture was the only source of prophetic truth, re-cast astrology as an old woman's superstition, and framed Luther as a dedicated opponent of stargazing. Under the pressures of the Thirty Years’ War, the Melanchthonian synthesis between astrology and the Gospel suffered further strains.

It is difficult, in a brief summary, to do full justice to Barnes's more detailed arguments. No scholar has so immersed himself in the ephemeral prognostications churned out in massive numbers by German printers, and Barnes's conclusions have profound importance not just for our understanding of the culture of German Protestants but also to the linked histories of astrology and prophecy in this period. He demonstrates abundantly the need to consider each region and confession as a separate case, and his concluding chapters bring fresh insight into the fraught question of the causes of astrology's decline. I have almost no critical remarks to make. Given the large numbers of publications that Barnes has examined, I found myself at times wishing for more of the sort of quantitative evidence presented in his graph of German annual practicas, especially in those moments where Barnes seeks to establish fundamental changes in the nature or tone of the prognostications and calendars. Contrary to Barnes's statement on p. 72, Albertus Magnus was not, like Roger Bacon, a proponent of ‘the horoscope of religions’, although he was certainly an avid supporter of the astrologers’ art. But these are minor quibbles in the face of a truly remarkable accomplishment. Astrology and the Reformation is a major work that will engage scholars for years to come.