But despite “bending over backward to contain randomness itself within the ambit of a purposeful natural order,”151 the scholastics found that, despite their best efforts, there remained observable phenomena stubbornly impervious to rational inquiry.152 These thinkers arrived, by necessity, at a compromise position. Thomas Aquinas, for instance, posited the existence of a middle ground between the natural and the supernatural, which he called the “preternatural.”153 In theory, preternatural objects and phenomena had natural qualities and operated in accordance with reason; but in practice, the scholastics admitted that they remained ignorant of the inner workings of these marvels. The invention of the category of the preternatural was to some extent a face-saving measure—it allowed the scholastics to remain committed to the proposition that everything had a rational explanation, while nonetheless admitting that there were phenomena that still needed to be more completely understood.
An object or phenomenon could fall into the category of the preternatural for a variety of reasons: for example, it might be subject to chance, to an unpredictable confluence of natural forces that cause it to behave as it does. The most common explanation, however, for why a preternatural phenomenon behaves as it does was the imputation to it of “occult qualities.” This designation, which continued to be invoked until well into the early modern period,154 essentially meant that the reason an object behaved in a certain manner was natural but inexplicable according to the known laws of natural causation. Or, to use the more technical language of the scholastics themselves, an occult quality was the “specific form” of an object or phenomenon, which conferred its particulars upon it; this stood in contrast to the “manifest properties” of natural objects, which could be accounted for by reference to their elemental composition. Scholastic thinkers sought to account in this manner for the routine, predictable, yet mysterious workings of seemingly supernatural phenomena.155
This sort of elite intellectual engagement with the wondrous and the occult had implications for the medieval conception of magic as well. Ever since the publication of Lynn Thorndike’s magisterial History of Magic and Experimental Science, scholars have increasingly come to recognize that magic was part and parcel of the medieval learned discourse over the workings of the natural order. Theologians, of course, were quick to condemn “necromancy,” magical praxis accomplished via the adjuration of demons, and magia could certainly be used as a term of opprobrium. But many theologians and natural philosophers alike tended to accept the validity and permissibility of so-called “natural magic,” which harnessed the occult properties of various objects in order to exploit natural “sympathies” and “antipathies” for concrete ends.156 Thus, the lines between what we would today call “science” and “magic” were for medieval thinkers very blurry indeed: lapidaries and medical treatises contained detailed descriptions of the amulets that could be made from various precious stones,157 and descriptions of materia medica in herbals were consulted by physicians and magicians alike.158 Pursuits such as physiognomy and, of course, astrology were also firmly within the “scientific” mainstream during this time period.159
Conceptually related to both occult “wonders” and natural magic was another discourse that flourished during this time period, but one which, at first glance, seems unrelated: technical, mechanical, and artisanal knowledge. In order to understand the linkage between these spheres, let us return briefly to occult properties. While the scholastics’ imputation of these hidden qualities to preternatural objects was intended to subsume those objects within the natural world, it also entailed a value judgment as to their status relative to other natural phenomena. For the scholastics, the theoretical, speculative via rationis (way of reason) was the favored intellectual approach; the via experimentalis (way of experiment), rooted in empiricism and induction, was far lower on the epistemological hierarchy. Preternatural objects and their occult workings could only be apprehended through empiricism—the attractive pull of the magnet could be seen, after all, but never derived from the known laws of nature. As such, writings about “marvelous” objects and phenomena were frequently grouped together with writings about other spheres of interest that were dependent upon observation of nature. The foremost example of this latter category was technical, artisanal crafts. After all, medieval artisans passed down their “trade secrets” from generation to generation, and developed new ones not via mathematical formulae or logical deduction, but through experimentation and careful observation. While discussions of casting spells, or of wondrous animals, might seem at first glance to have little to do with horticultural guidance or recipes for tanning solution, all of these contents were often grouped together in medieval writings on account of their shared epistemological foundations. Indeed, the curricular divisions of knowledge that can be found in works like William of Conches’s Philosophia mundi tend to subsume “magic” within the “mechanical arts” rather than in the Trivium or Quadrivium—attesting to the perceived linkages between empiricism, mechanical knowledge, and the occult.160
In fact, this period saw the growth of an entire genre of literature devoted to precisely these subjects, namely the “books of secrets.”161 Along with discussions of “marvelous” natural objects and their uses, these collections also contained a mix of recipes for medicines, spells, and instructions on how to master a wide array of crafts. Despite (or perhaps because of) their purportedly esoteric nature, these books were extremely popular in the medieval period—even among the scholastics, many of whom devoted considerable attention to these texts and their contents.162 Certain especially popular books of secrets even achieved quasi-canonical status among the university students and scholars. The extremely influential Pseudo-Aristotelian Secretum secretorum (Secret of Secrets), for instance, has survived in so many manuscripts that Thorndike declared it “the most popular book in the Middle Ages.”163 This text, a “mirror for princes” supposedly composed by Aristotle for the use of his pupil Alexander the Great, combines basic political and moralistic guidance with medical, alchemical, and physiognomic contents and sundry magical spells. The very fact that it was attributed to Aristotle, and flourished among clerics and university scholars alike, attests to the fluid boundaries during this period between magic, science, and the occult.164
Scholars of medieval and early modern Jewish culture have increasingly explored the fluidity between medieval Jewish “science” and “magic.” Today it is a commonplace, for example, that the rationalist philosopher Moses Maimonides’ famous condemnation of astrology as a pseudoscience was well beyond the mainstream of medieval Jewish scientific discourse, and that influential thinkers from Abraham Ibn Ezra to Abraham Bar Hiyya to Gersonides all considered astrology to be a—even the—valid approach to understanding the natural world, useful for scientific, medical, and theological purposes alike.165 Occult properties—known as segulot—were seized upon by Jewish thinkers just as they were by their Christian contemporaries, and amulets and talismans were endorsed as medically effective and well within the contemporary definition of “rationality.”166 For philosophically minded Sephardic thinkers, then, as for high medieval scholastics, the ostensibly “magical” and occult could be readily subsumed within a stable and comprehensible natural order.
Awareness of this cultural and intellectual backdrop casts the Pietists’ preoccupation with both routine and