Encyclopedia of Early Modern Philosophy and the Sciences

Living Edition
| Editors: Dana Jalobeanu, Charles T. Wolfe

Books of Secrets and Vernacular Knowledge

  • William EamonEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-20791-9_240-1

Introduction: A Sixteenth-Century Publishing Phenomenon

From the mid-sixteenth century on, the early modern European book market was inundated with cheaply printed compilations of recipes and experiments known as “books of secrets,” which were printed continuously into the eighteenth century. These popular works contained hundreds of medical prescriptions along with technical recipes relating to metallurgy, alchemy, dyeing, perfumery, cosmetics, and other arts. From the books of secrets readers could learn about new chemical technologies such as distillation, secret remedies for common ailments, and natural magical “experiments” for wonder and delight. The books of secrets communicated much practical information to new and upwardly mobile middle-class readership, leading some historians to link them with the secularistic values emerging in the early modern period and to see them as expressive of a new “age of how-to” (Eamon 1994a).

However, the books of secrets were not in all instances mere how-to books. While many were simple technical books for artisans and householders, others, in particular those associated with the natural magic tradition, professed to make serious contributions to natural philosophy, as science was then called. Underlying the books of secrets as philosophical works was an implicit metaphysical claim and an epistemological premise: first, that nature is a repository of occult forces; and second, that these hidden forces might be discovered and exploited for human gain by using the right methods and techniques. The utilitarian character of the books of secrets gave substance to these claims. Unlike the more recondite contemporary treatises on magic and the occult arts, the books of secrets were grounded upon concrete experimental results. At the same time, the books of secrets popularized the new experimental methods to the lay public.

The Secrets of Alessio

The most famous sixteenth-century book of secrets was a work published in 1555 under the pseudonym of Alessio Piemontese, I Secreti del reverendo donno Alessio Piemontese. Alessio’s Secrets was a compilation of recipes including remedies for various common ailments and instructions for making ink, dye, perfume, cosmetics, jewelry, and other craft articles. Beginning with a recipe for a “precious balm” that will preserve youth and hold back old age and ending with a chapter on metallurgy, the recipes range from the mundanely practical, such as one for making scented soap, to the utterly fanciful, such as Alessio’s favorite, “oil of a red dog,” an ointment made by boiling a red-haired dog until it falls to pieces, then adding scorpions, worms, pig marrow, and a number of plants in a prescribed order. With this precious balm, Alessio testifies, he treated a monk’s withered arm, “dried up like a stick,” and a Portuguese man who suffered from gout. Despite such farfetched claims – or perhaps because of them – the Secreti went through more than a hundred editions in multiple languages and was still in print in the 1790s. Alessio also served up recipes for making orange and quince jam “the Spanish way,” betraying the work’s Neapolitan origins. The humanist Girolamo Ruscelli (1500–1566), the real author of the Secreti, later reported that Alessio’s secrets were in fact the experimental findings of an “Academy of Secrets” that he and a group of humanists founded in Naples in the 1540s (Eamon and Paheau 1984). Ruscelli’s academy (if it existed) is the first recorded example of an experimental scientific society. The academy was later imitated by the Neapolitan magus Giambattista Della Porta, who founded an Accademia dei Secreti in Naples in the 1560s (Eamon 2017; Badaloni 1960).

Besides publishing scores of recipes, some practical and others hardly credible, Alessio’s Secreti addressed a vexing ethical issue regarding secrecy and knowledge. Should valuable knowledge be kept secret so as not to cast pearls before swine; or should secrets be published widely so that all people can benefit from them? The preface to the Secreti addressed this perennial question with a parable in which the fictional Alessio sorrowfully recounts that, by refusing to give up one of his secret cures, he inadvertently causes the death of a craftsman suffering from a bladder stone. In deep remorse, Alessio retreats to a monk’s cell to live like a hermit, and vows to publish all his secrets so that others might benefit from them, while acknowledging that once published his rare and precious secrets would be cheapened.

Alessio’s yarn created a compelling portrait of a new type of scientific investigator. In contrast to the medieval man of science – the contemplative scholar who did science from his study – Ruscelli portrayed Alessio as a daredevil experimenter who roamed the world in search of the secrets of nature. Disregarding the scholar’s temptation to bow to authority, Alessio deliberately sought secrets “not just from great men of learning and grand lords and ladies, but from poor women, artisans, country folk, and all sorts of people” (Ruscelli 1558: 4). The Secreti extolls the empiricism of practical people – vernacular knowledge – and subtly shifts the criterion of truth from logical certainty (scientia) to practical productivity, a viewpoint that would come to fruition in the philosophy of Francis Bacon, who urged philosophers to compile histories of the mechanical arts. The books of secrets endorsed a vernacular way of knowing, an epistemology grounded on seeing, sensing, and understanding through a bodily relation with nature (Smith 2004).

The Professors of Secrets

Alessio’s Secreti unleashed a torrent of books of secrets. Tens of thousands of copies of these cheaply printed books streamed from the presses in the sixteenth and seventeenth centuries (Ferguson 1959). “Alessio Piemontese” became a household name throughout Europe and his book was imitated by countless authors. The popularity of books of secrets spawned a new scientific identity: the “professor of secrets.” Intrepid experimenters, the professors of secrets flaunted their contempt for received authorities, whether of physicians or scholars, and proclaimed their adherence to the empiricism of the piazzas and the “way of nature.” They extolled experiments and published hundreds of them in the form of recipes, both borrowed and invented.

The professors of secrets were, literally, creations of the books of secrets. So dubbed by Italian friar and social critic Tomaso Garzoni, the professors of secrets were new entrants onto the social and literary scene of early modern Europe. Among the more than 500 different “professions” that Garzoni enumerated in his kaleidoscopic Piazza universale di tutte le professioni del mondo, the professori dei secreti (professors of secrets) shoved their way onto the great piazza of contemporary society and proclaimed their secrets on the streets and in the taverns and pharmacies and published them in books that were entertaining and easy to read. Garzoni created an indelible portrait of them as a community of hypercharged experimenters who burned with such passion for secrets that “they yearn for them more than life’s daily necessities” (Garzoni 1996: 324).

Alessio was the prototypical professor of secrets. His fervent hunt for secrets described in the preface to the Secreti gave rise to a legend of the wandering empiric in search of technological and scientific secrets. Because of its popularity, the work helped usher in the conception of science as a hunt for the secrets of nature. The idea of science as a hunt pervaded experimental science during the Scientific Revolution and continues to inspire modern scientists (Eamon 1994b).

Vernacular Knowledge

In their call to move away from armchair philosophy, the professors of secrets praised the practical empiricism of the piazza – anticipating Francis Bacon declaration that “maker’s knowledge” was superior to mere reflection. Knowledge that makes something useful, Alessio implies, is more valuable (and therefore more true) than the empty knowledge judged to be true by Scholastic standards (Pérez-Ramos 1988). Admitting this kind of knowledge into natural philosophy was problematic. Galileo, while praising the Venetian Arsenal as a font of empirical information, left little doubt that geometrical demonstrations were superior to mechanics’ knowledge (Galileo 1638/1974). Empirical knowledge gained in the piazza did not count as knowledge until a recognized authority vouchsafed for it.

The books of secrets were an important medium through which craft information penetrated letters. Intellectuals were as keenly interested in practical knowledge – whether how to dye a beard or make proper ink – as ordinary people. Patrons paid attention, and scientific research slowly shifted to encompass the practical needs of merchants, towns, and courts. Books of secrets continued to find an audience and technological treatises on specialized trades appropriated recipes from them. Traces of books of secrets can be detected in many technical manuals, such as Vannoccio Biringuccio’s Pirotechnia and Antonio Neri’s treatise on glass, L’arte vetraria (1612), which so impressed the young prince Federico Cesi that he invited Neri to become a member of his newly formed experimental academy, the Lincei (Academy of Lynxes). Cesi recognized that recipes were, in effect, prescriptions for experiments (Neri 1612/1980).

Books of Secrets and Magic

In the books of secrets, experimental science shaded into natural magic. Giambattista Della Porta’s famous Magia naturalis (1558) deployed practical recipes in an effort to demonstrate the principles of natural magic. Other books of secrets, such as Isabella Cortese’s Secreti (1564), a compilation of alchemical recipes, disseminated experimental techniques and practical information to a wide readership. Recent research has suggested that the books of secrets played an important role in the emergence of early modern experimental science, acting as intermediaries between the private and esoteric secrets of medieval alchemists and magi and the public Baconian experiments that characterized the research programs of the Royal Society of London and other seventeenth-century experimental academies.

Books of secrets were about “secrets” in two senses. First, they published proprietary techniques and remedies that were unique in some way or composed of “secret” ingredients. They were also secrets in the sense that no one could explain their efficacy through logical reasoning or appeal to authority. The professors of secrets asserted that their experimental methods enabled them to access nature’s hidden powers, a methodology at odds with the scientific establishment. Yet the works of professors of secrets such as Leonardo Fioravanti, Europe’s most famous professor secrets, were sensational. Fioravanti, the self-proclaimed founder of a “new way of healing,” used print and chymistry to market himself, a strategy that made him a famous author and opened the door to the court of King Philip II of Spain (Eamon 2010).

Common Experimenters

According to Ruscelli the goal of the Academy of Secrets was not simply to publish a collection of useful and tested recipes but also to acquire conoscenza di sè, or self knowledge. Since humanity is a microcosm reflecting all the attributes of the macrocosm (the universe), Ruscelli maintained, the route to self knowledge is through the study of nature – a concept that descends from the philosophy of the southern Italian philosopher Bernardino Telesio (1509–1588), whom Bacon dubbed “the first of the moderns” (Van Deusen 1932). Telesio’s major philosophical treatise, De rerum natura, was a frontal assault on Aristotelianism, and the philosophical naturalism he espoused was shared by thinkers as diverse as Girolamo Cardano, Giordano Bruno, Giambattista Della Porta, and Tommaso Campanella. Inspired by Telesian metaphysics, the Accademia Segreta dedicated itself to experimental research aimed at fulfilling the promise that, in the minds of Neapolitan contemporaries, Telesio’s philosophy held out.

Ruscelli defined the object of the Segreti’s research as making “anatomies of nature.” How he and his fellow academicians thought such “anatomies” might be carried out is revealed by the recipes in Alessio’s Secreti and Ruscelli’s Secreti nuovi. The vast majority of the operations described in these and other books of secrets were alchemical in nature. Distillation occupies a prominent place and considerable space is given to metallurgical processes involving alchemical operations. For the professors of secrets alchemy was a vehicle of self-fashioning and an expertise that set one apart from the crowd.

Alessio’s Secreti became a model for countless books of secrets published all across Europe in the sixteenth and seventeenth centuries. They ranged from the chapbooks touting marvelous cures that charlatans sold in the piazzas, such as the Venetian Lorenzo Leandro’s Tesoro di varij secreti (Treasury of Various Secrets), to pretentious philosophical tomes such as Levinus Lemnius’s Occulta naturae miracula (Secret Miracles of Nature) and Johann Jacob Wecker’s massive De secretis, which claimed to reveal deeply hidden secrets of nature. Though distant from one another by language and degree of learning, they shared the belief that nature was a repository of secrets that could be discovered and put to use. The hunt for the secrets of nature was an enterprise undertaken by popular and learned cultures alike.

Previous generations of historians tended to see the history science as a branch of intellectual history; thus when Alexandre Koyré coined the term “scientific revolution” to define the fundamental transformation that came as a result of the “mathematization” and “mechanization” of the Western “world-view,” he intended to define a purely intellectual change. Recent generations have come to see science not exclusively as a set of theories but as a range of practices engaging with the material world, sharing information and objects as well as mutual understandings (Cook 2007; Smith 2004). In this context, vernacular knowledge – the knowledge and experiences gained from practical pursuits and everyday interactions in the marketplace – is being taken seriously as contributing to the birth of modern science. A growing scholarly interest in the books of secrets, opening up to historians a world of “common experimenters,” is one indication of that historiographical shift (Leong and Rankin 2011).

The Secrets of Nature

The idea that nature keeps secrets was hardly new in the Renaissance. “Nature loves to hide,” Heraclitus is supposed to have said in an aphorism that generations of philosophers puzzled over. The Roman poet Lucretius, in De natura rerum, affirmed that “jealous Nature has hidden the spectacle of atoms from our view” (Hadot 2006). But the secrets of nature metaphor had little import in medieval philosophy. Theologians such as Lactantius held that nature’s secrets were divinely hidden; while Scholastics argued that nature was not a secret but understanding of it was reserved for the intellectual class. Though Roger Bacon deployed the metaphor in his treatise, Secretum secretorum, the work, a sort of “middle-brow classic,” had little influence on Scholastic natural philosophy.

Historically, the secrets of nature metaphor have played upon two different senses of the concept of secrecy, one epistemological and the other sociological. One implies that nature is inherently arcane, the other that natural knowledge is privileged. One sense of the metaphor says something about nature itself, while the other makes a statement about the ownership of scientific knowledge and the practice of esotericism. Is nature inherently occult, or does it merely seem so, a consequence of the imperfect state of human knowledge?

The early modern period added a new implication to the secrets of nature metaphor: the idea of a secret as a technique or recipe, the sense in which the word was deployed in the books of secrets. According to this sense of the metaphor the secrets of nature implied nature’s inner workings. Thus Francis Bacon spoke of penetrating nature’s workshop to learn its secrets (Klein 2008). Underlying this sense of the metaphor was the view that nature could be understood in mechanical terms as a set of invisible techniques nature employs for producing its sensible effects. The goings-on in “nature’s workshop” might be replicated just as one might replicate a technique by following a recipe. This sense of the secrets of nature metaphor set a new research agenda for early modern science. Whereas the Scholastics regarded occult qualities as unknowable and out-of-bounds for natural philosophy, the new philosophers rejected the Scholastic doctrine of occult qualities on the grounds that it was, in the words of English virtuoso Walter Charleton, nothing more than a “sanctuary of ignorance.” According to Charleton, who like many contemporaries espoused the corpuscular or atomist philosophy, the goal of natural philosophy was to “withdraw the thick curtain of obscurity which yet hangs betwixt Nature’s Laboratory and us” so as to get a glimpse at how nature operates (Charleton 1654: 342).


Long forgotten or ignored, early modern books of secrets have recently become subjects of intensive historical research. As long as the history of science was regarded solely as a branch of intellectual history, and scientific change purely as theoretical transformation, books of secrets, though always rattling in the background, were never taken seriously. It was only when historiography took a “cultural turn” in the 1990s that books of secrets became of interest to historians. Recent studies of books of secrets have opened up new lines of inquiry in the history of philosophy and science. Interest in artisanal knowledge has resulted in surprising discoveries about the contribution of craftsmen to the scientific revolution. Books of secrets, many of which were written by women, also shed light on the role of gender in the production of scientific knowledge (Leong and Rankin 2011). Reflection on books of secrets has also led to reassessments of the place of secrecy in the early modern economy of knowledge. Some of the new studies challenge long-accepted assumptions about the history of science and modernity, such as the conventional wisdom equating openness with progress and secrecy with regression. That assumption turns out to be only relatively true. To some, including outsiders such as Jews, the premodern economy of secrets was just as advantageous as a system that propagated open knowledge (Jütte 2015: 249).

Books of secrets continued to be published until well into the nineteenth century, but by then had lost any credible claim to revealing the secrets of nature. No longer considered scientific or experimental, the modern descendants of books of secrets are now found in bookstores shelved under the section labeled How-To.


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Authors and Affiliations

  1. 1.New Mexico State UniversityLas CrucesUSA

Section editors and affiliations

  • Cesare Pastorino
    • 1
  1. 1.Wissenschaftsgeschichte/History of ScienceTechnische Universitaet BerlinBerlinGermany