The Church’s victory in the “Investiture Controversy,” throwing off the domination achieved over it by secular powers following the death of Charlemagne, made it the first domain to successfully assert the right to manage its activities in accord with its own principles. But victory was only partial, leaving spiritual and secular powers facing each other across a field of constantly shifting relationships, giving heterodoxy more room to survive than elsewhere. An early example was the contrast between European universities, established as associations of teachers and students formed to assert autonomy from town authorities, and Islamic madrasas subject to direction by their elite patrons. When the corpus of Aristotelian texts became available, first in Arabic and later in Latin, it was first greeted with enthusiasm by readers of both, followed by suspicion because Greek materialism posed threats to religious doctrines. In Muslim lands, this led to a widespread rejection of philosophical inquiry as a path to truth; in Europe, attempts to impose similar restrictions failed, because university faculties resisted the claims of churchly conservatives to limit what could be taught. In this situation, scholastic speculation generated radical ideas about cosmology and physics, foreshadowing the break with traditional cosmology two centuries later.

Historiography concerning the relationship (or non-relationship) between magic (or the “occult”) and “science” was dominated in the 1960s-1980s by the “Hermetic” thesis of Frances Yates and its critics (including Robert Westman and Brian Vickers). Vickers in particular argued that the “occult” and the “scientific” are separate “mentalities” or paradigms. This chapter considers an alternative view. By tracing the fortunes of the theory of radiative virtue advanced by the ninth-century Arabic philosopher al-Kindi, which began as a “theory of the magical arts” providing a physical basis for magical operations, we can see that some “magical” ideas connected with the astrological theory of “celestial virtues” influenced later natural philosophy. Al-Kindi’s suggestion that all causation in the elemental world was effected by means of rays was taken up in the medieval perspectiva tradition, and elaborated into a theory of astral magic by John Dee, but continued to provide a model for action at a distance in the mechanist theories of seventeenth-century natural philosophers, such as Kenelm Digby, Walter Charleton, and—ultimately—Isaac Newton, who believed that the corpuscles of all bodies acted at a distance by “certain Powers, Virtues, or Forces” in a similar way to the rays of light.

Chapter 3 gives an account of the transmission of Islamicate meteorology into Northern and Western Europe. An early phase was the collection and study of the texts known as the Alchandrean Corpus, which provided short introductions to topics within astronomy and mathematics. The chapter then considers twelfth-century translations of more advanced works, and especially of treatises on weather-forecasting. The contributions of Petrus Alfonsi, and the reception of Latin translations of Arabic versions of the works of Ptolemy, are discussed. The chapter argues that it was this period that saw the creation of Latin, Christian forms of astrologically based weather forecasting. Moreover, this was no transitory fashion, and the new, astrometeorology remained dominant until the seventeenth century. Central to this new science was the application of fundamental works by Ptolemy, and this is considered in detail. The final part of the chapter gives an outline of the works of Islamicate astrometeorology that were translated into Latin, and especially of the theories of al-Kindi. The conclusion is that Latin writers and translators searched out works on weather forecasting, and rapidly began to produce their own versions.