One of the most intriguing and peculiar aspects of Della Porta’s Magia natu­ralis libri XX is that its author presented this work as the fruit of the collective efforts of an “Academy of curious men,” known as the Academia Secretorum Naturae. Della Porta emphasized that the twenty books of the Magia naturalis resulted directly from the cooperative endeavours within this academy, which he established at his Neapolitan residence sometime after 1560. This collective, empirical work was fundamental to the expansion of the Magia naturalis from its initial four-book format to the comprehensive twenty-book edition.

This communal approach challenges the conventional image of the solitary Renaissance sage. The Academia Secretorum Naturae thus serves as a critical lens through which to examine Della Porta’s methodological framework. It highlights how his natural philosophy was rooted not only in ancient texts and theory but equally in a practical, collaborative experimentalism unique to the Neapolitan intellectual environment. The Academy provided a structured space for shared inquiry and empirical verification, where knowledge was generated through collective observation and exchange, guided by Della Porta’s coordinating role as the magus.

In the Preface to the Reader of Magia naturalis libri XX, Della Porta explicitly acknowledged this cooperative nature, stating that he spared “no pain nor cost,” and that the “labours, diligence, and wealth” of “most famous nobles, potentates, great and learned men” assisted him, specifically naming Cardinal d’Este as a patron. He further noted that the members of his academy “cheerfully disbursed their money” and exerted their utmost endeavours to assist him in compiling and enlarging the volume (Della Porta 1589; Porta 1658, Preface to the Reader, s. p.). This made Magia naturalis libri XX not merely a text, but effectively both the product and the culmination of a collaboratively funded and coordinated experimental endeavour within his Academy.

Della Porta referenced the Academy not only within the pages of his Magia naturalis libri XX but also in his correspondence, further underscoring its active role in his scientific pursuits. Two letters from Della Porta to Ulisse Aldrovandi and Federico Cesi confirm that the Academy included an expert distiller, Giovanni Battista Melfi, and a herbalist, Flavio Giordano (Eamon 1994, 402).

Yet, this emphasis on collective inquiry was not an innovation born in a vacuum; its roots lay deep in the intellectual environment of Naples and in Della Porta’s own early development. Even the first Magia naturalis originated in a collaborative context, with Della Porta benefiting from the invaluable support of mentors such as his older brother Giovan Vincenzo or the alchemist and philologist Domenico Pizzimenti (Badaloni 1959–1560; Eamon 1994, 201; 2017). Furthermore, a collaborative and experimental approach to the secrets of nature was already in vogue in the Kingdom of Naples well before Della Porta founded his own academy. Consider, for example, the “Academia secreta” that Girolamo Ruscelli discusses in his Secreti Nuovi, probably active in Salerno in the years when Della Porta was still a young man.6

William Eamon suggests that this earlier academy may have benefited from the financial patronage of Ferrante Sanseverino, Prince of Salerno (1507–1568). Eamon dates the activity of this academy to the decade between 1542 and 1552, coinciding with Sanseverino’s shift in allegiance to Henry II of France. Although Della Porta was quite young during this period, Eamon suggests the possibility of his participation or at least exposure to its activities, perhaps in the company of his elder brother, Giovan Vincenzo (Eamon 1994, 197–200). Regardless of Della Porta’s actual participation in the academy, or even its definitive existence and location, it is highly plausible that the program described in the work published by Ruscelli in 1567 profoundly influenced Della Porta ideologically, inspiring the structure and aims of his own academy as outlined in the Preface to the reader of the Magia naturalis of 1589. Ruscelli, in his detailed account of this earlier Academy’s operations, clarifies the rationale behind the name “Secreta.” Far from signifying structural esotericism—a permanent and inherent secrecy—the underlying principle was a commitment to making their discoveries public once they had been rigorously proven through collective experimentation and deemed worthy of dissemination to the “world.” The secrecy, therefore, was a temporary and provisional stage, awaiting the moment when discoveries could be tested, validated, and then made public (Ruscelli 1567). The research program of this earlier Academy emphasized the interconnectedness of natural knowledge and Socratic self-knowledge, proposing that understanding the “Great Animal,” the universe, would illuminate the nature of the microcosm, or humankind, through analogy (Badaloni 1959–60). Crucially, this model of secrecy—as a provisional stage reserved for the internal process of experimentation and validation before public disclosure—would become a key feature within Della Porta’s Academia Secretorum Naturae (Della Porta 1589). This shared understanding of provisional secrecy established one of the key methodological connections between the two academies, despite their temporal and operational differences. Furthermore, their methodology, which centred on direct experimentation to verify information presented in ancient and medieval scientific encyclopaedias, is a methodological feature that Della Porta would clearly adopt and extend in his own Magia naturalis.

This defining methodological link is corroborated by Pompeo Sarnelli, the editor of the Italian Magia naturale in 1677, whose widely-cited account later became a crucial source for scholars. Sarnelli writes that Della Porta, “not satisfied with his own intelligence, submitted his opinion to some more cultivated men, for whom he had created an academy in his home, called the “Academy of Secrets” (de’ Secreti). And these men vied with each other to add new discoveries to his researches, which, being thoroughly examined by the academy, were “with satisfaction established at a later time” (godevano poscia di vederle stabilite) (cf. Della Porta 1677, Pompeo Sarnelli A’ lettori, b). This process—where new findings were first thoroughly examined by the collective before being established—confirms that the Academy’s secrecy, like Ruscelli’s model, was a temporary phase of internal empirical validation preceding public disclosure.

Beyond the methodological precedents like Ruscelli’s academy, equally important was the medical academy formed, in Naples, around Leonardo Fioravanti, a celebrated and controversial physician, surgeon, and alchemist who travelled extensively throughout Italy. Fioravanti’s empirical and vernacular approach made him a central figure in the popular diffusion of medical and natural secrets.7 As Fioravanti himself tells us, his Neapolitan home hosted an informal circle of physicians and alchemists dedicated to the study of the secrets of nature. These are environments that we cannot exclude that Della Porta may have frequented as a teenager, illustrating a context, that of sixteenth-century Naples and its Kingdom, highly characterized by a collective and choral approach to the construction of new knowledge.8 Indeed, Eamon has cautiously hypothesized a direct meeting between Fioravanti and Della Porta between 1550 and 1555, identifying the latter with a Neapolitan who allegedly showed Fioravanti a “magic mirror” during his stay in the city (Eamon 2010, 120–21). While Della Porta’s direct encounters with Fioravanti remain hypothetical, Fioravanti’s own connections to two key figures in Della Porta’s formation, Donato Altomare (1520–1566) and Giovanni Antonio Pisano, are certain; Fioravanti himself mentions them in his works, Tesoro della vita humana and Fisica, respectively.9 These figures were crucial links in Della Porta’s early intellectual network: Altomare, a prominent physician and professor of medicine at the University of Naples, represented the connection to the formal academic sphere, potentially influencing Della Porta’s initial training in fields like anatomy. Pisano, who was a Protomedico and a Reader of Practical Medicine at the Neapolitan University, reinforced the young polymath’s exposure to the artisanal and empirical aspects of magia naturalis. The documented presence of these scholars in both Fioravanti’s and Della Porta’s orbits further confirms that Della Porta’s early collaborative ethos was deeply rooted in the interconnected intellectual landscape of Renaissance Naples.

Complementing these external networks, Della Porta’s own household constituted an intellectual hub of comparable significance. Thanks largely to the influence and wide-reaching connections of his elder brother, Giovan Vincenzo—it had, from his earliest years and well before the founding of the Academia Secretorum Naturae, become a vibrant meeting place for magicians, experimenters, and seekers of nature’s hidden truths from across the Kingdom of Naples. It was within this intellectually charged and dynamic environment that Della Porta’s scientific imagination first took root and began to flourish (Verardi 2018).

This broad intellectual synergy, which characterized the porous landscape of sixteenth-century Naples, found one of its clearest expressions within the university context in the work of Francesco Storella—professor of Logic in both Salerno and Naples, and one of Giordano Bruno’s earliest mentors. In his commentary on the 1555 edition of the Secretum secretorum, Storella reimagines Aristotle through the prism of the Hermetic tradition, portraying him as a natural magician and disciple of Hermes. Under Storella’s guidance, Aristotelian philosophy was reinterpreted as a rational foundation for natural magic, alchemy, and empirical science (Verardi 2023). This critical reinterpretation demonstrates how Aristotelianism itself was actively furnishing the intellectual justification required to elevate natural magic to a legitimate, rational discipline within the academic sphere.

The permeable and open nature of the Neapolitan academic environment is well-exemplified by the intellectual relationship between Della Porta’s alchemy teacher, Domenico Pizzimenti, and Storella. Pizzimenti collaborated closely with Storella, demonstrating how easily the Neapolitan university context integrated with non-academic environments dedicated to alchemical experimentation. Pizzimenti, celebrated for his edition of the Democritus Abderita de Arte Sacra, sive de rebus naturalibus,10 publicly praised Storella for his sharp logical abilities in Storella’s own writings. Pizzimenti penned an encomium for Storella’s Logicalium capitum Decas prima, published in 1555 (Storella 1555, 18v). That same year, Storella also released his edition of the Secretum secretorum. What’s more, a fourteen-verse poem by Pizzimenti graced the Secretum’s preface, offering praise to Ettore Pignatelli II, Duke of Vibo Valentia (Aristotle 1555), the father of the Ettore Pignatelli who would later participate in the Accademia degli Oziosi with Della Porta. Crucially, Pizzimenti’s established philological expertise suggests that his collaboration with Storella was deep, extending to the critical textual analysis and interpretation of the Secretum’s sources, thereby merging alchemical practice with academic textual authority.

In those same years, Pizzimenti also exerted a formative influence on Della Porta. Della Porta and Pizzimenti engaged in alchemical experiments together. According to Nicolás Guibert’s later account in De interitu alchimiae (1614, 135–36), the third book of Della Porta’s Magia naturalis libri IV—which addresses the transmutation of metals—was actually written by Pizzimenti himself and published under Della Porta’s name. While the idea that the book was solely the work of Pizzimenti seems exaggerated, it is certain that it was born through the collaboration of the young Della Porta, then a magus in training, with Pizzimenti, his master of alchemy. Through this partnership, Pizzimenti served as a vital intellectual bridge, seamlessly connecting the theoretical Aristotelian reform initiated by Storella within the university setting with the practical, hands-on alchemical experiments conducted at Della Porta’s home during the latter’s youth. This was a defining convergence, as Pizzimenti’s philological expertise brought the critical tools of textual scholarship directly into the laboratory of the alchemist and natural magician. This foundational collaboration continued into the active years of the Academia Secretorum Naturae, extending at least into the 1570s, thereby reinforcing the peculiar, shared spirit of empirical inquiry, forged by philosophy, philology, and experiment, that defined Della Porta’s intellectual project.

The ideological commitments inherent in this partnership—particularly the strong favor toward the secret dimension of alchemical research found both in the Secretum secretorum edited by Storella and in Pizzimenti’s own works—constitute a vital, counterbalancing influence to the principle of provisional public disclosure. This intellectual environment likely fueled the hesitations toward complete openness that are discernible in Della Porta’s first edition of the Magia naturalis (1558), written during the peak of Storella and Pizzimenti’s activity in Naples. These initial reservations regarding full disclosure were gradually diminished but left elements of conflict and contortion within the Magia naturalis of 1589, as seen in the explicit calls for the necessary protection of knowledge from the “profane.” This in turn mirrored the general atmosphere of the Counter-Reformation and the enforced secrecy regarding certain scientific and magical pursuits.

The internal tensions surrounding disclosure and the protection of knowledge, explored in the previous section, were not oppositional forces hindering Della Porta’s intellectual project; rather, they existed as a necessary friction accompanying his radical commitment to the empirical investigation of secrets and the rationalisation of magical practice.

While Della Porta’s Magiae naturalis libri XX certainly drew from a shared European heritage of natural magic, from Ficino to Agrippa (Balbiani 2001; Zambelli 2007; Verardi 2022), it uniquely combined this tradition with a Peripatetic, empirical natural philosophy whose specific methodological justification was forged in the unique intellectual milieu of Naples.11 This philosophy provided an open and adaptable framework that permitted the seamless incorporation of contemporary medical and chemical innovations, particularly the medical iatrochemistry of Paracelsus (Clericuzio 2024). This integration enhanced his empirical range without fundamentally disrupting the Peripatetic physical system of his natural magic. This vision of a broad, open, and synthetic natural philosophy was a prototype of intellectual freedom and adaptation, which, through its own peculiar and distinct directives, would be widely developed among investigators of nature in the century to come.

This innovative approach not only echoed but also surpassed Ruscelli’s program of science as venatio—a hunt for new natural secrets—12 by providing a complex balance between the theoretical justification for research and its experimental development, all structured from a logical perspective.

Della Porta was uniquely positioned to synthesize ideas from a vibrant intellectual milieu where significant advancements in Aristotelianism across Italy, particularly in Naples through figures like Storella, sought to revitalize logic, making it relevant to empirical inquiry rather than mere abstraction. This practical inclination is clearly demonstrated by Storella’s decision to reprint not only Aristotle’s Secretum but also Hippocrates’ Secrets and Averroes’ treatise on poisons, underscoring the strong medical and practical underpinnings of his work (see Verardi 2023). Della Porta built upon this movement, actively participating in it (a participation facilitated by the mediation of his master, Pizzimenti), reinterpreting it with original and unique directives. He emphasized that while science, as taught by Aristotle, is the knowledge of causes, for the natural magician this knowledge must specifically target the “sufficient cause” of “natural substances,” focusing on their manifest and occult qualities observable through experimentation. He rigorously applied the syllogism as a cornerstone of his work, particularly in his influential treatises on physiognomy, which explored the visible and hidden virtues of plants, animals, and humans. This commitment, which provides the precise practical implementation of the logical reforms championed by Storella and transmitted through their mutual contact Pizzimenti, is encapsulated in his assertion: “Experientia sine ratione manca est, etsi experientia sit artium omnium fundamentum, tamen sine ratione claudicat”—underscoring that while experience is fundamental, it is incomplete without reason, understood as the syllogistic method applied to the search for natural causes (Della Porta 2003, 13). Indeed, this philosophical justification was already present at the opening of the Magiae naturalis libri IV (1558), written in the years when Pizzimenti’s influence was most active. Della Porta’s assertion in that preface—that “Those who do not believe in the miracles of nature are somehow attempting to abolish philosophy” (“Qui enim naturæ miraculis fidem non adhibent, ii modo quodam philosophiam conantur abolere”)—perfectly encapsulates this joint intellectual mission (Della Porta 1558, Praefatio, s. p.).

This emphasis on rational inquiry and empirical verification did not, however, lead him to dismiss ancient wisdom. On the contrary, Della Porta held deep respect for the tenets of classical natural philosophy and medicine. His engagement with these foundational texts, alongside his experimental drive, highlights a delicate balance: he saw ancient knowledge not as a static dogma, but as a crucial, historical starting point that required careful selection. This involved recognizing a community of credible natural philosophers—extending from the past to his contemporaries—whose contributions served as a filter against false beliefs. For Della Porta, natural history played a fundamental role in this critical evaluation, ensuring that knowledge to be preserved was tested, refined, and expanded upon through relentless experimentation, guaranteeing a balanced and historical progress of knowledge. For Della Porta, the wisdom of the past and the novelty of discovery were not in opposition, but rather complementary forces driving the advancement of knowledge.

This peculiar openness is precisely what illuminates the distinctive interpretation he gave to the cardinal notion of natural magic: the principle of “sympathy.” This concept—the very fulcrum of the natural magic of Ficino and Agrippa (whom Della Porta knew well)—was widely accepted at the time also by many sixteenth-century Aristotelians, especially in medical contexts, and was central to pseudo-Aristotelian texts he considered authentic, like the treatise on physiognomy or the Secretum secretorum.13 For Della Porta, this principle, far from any spiritual or supernatural interpretation, was a cardinal law of the cosmos that gave the surrounding world an ontological unity, “regulating” the natural magician’s research. At the same time, the principle of resemblance served as a compass, allowing him to navigate the inexhaustible variety of natural phenomena (see Verardi 2018, 121–22). This philosophical approach provided a robust yet flexible foundation for his diverse investigations. Enriched by a profound knowledge of disciplines such as astrology, medicine, alchemy, herbal physiognomy, optics, and mechanics, the natural magician “perfected” this open and elastic natural philosophy by integrating it into a plural, collaborative, and experimental framework (see Verardi 2023; Eamon 2023).

This ideological and methodological innovation allowed Della Porta to reframe the very idea of magic, rendering it cooperative and experimental. In doing so, he implicitly redefined “nature” and “natural” by subjecting their very definition to an experimental process that was at once individual and collective. In Magiae naturalis libri XX, the idea of nature—like that of natural philosophy itself—became historical, provisional, and in fieri, subject to the continuous acquisitions and “proofs” of the venatio of the experimenters, the hunters of secrets. This is a “hunt” that now also makes use of a techno-magical approach,14 an indispensable aid for the experimental magus in imitating and potentially surpassing the wonders of nature,15 whose role as coordinator ensured that discoveries were systematically organized and verified. Della Porta writes: “I will set down what both I myself have done in it, and what I have received from other friends: I have performed the best I could, to shew others an opportune way of making better” (Porta 1658,186; 1589, 123).

While Della Porta celebrated collective inquiry and the exchange of empirical knowledge, he nonetheless assigned to the magus naturalis a decisive role as interpreter and guarantor of truth. This guardianship was not merely philosophical; it carried a profound ethical weight regarding who received what knowledge. The natural magician did not merely collect secrets; he organised, tested, and philosophically validated them within a rational and historical framework. Knowledge, for Della Porta, emerged from collaborative efforts yet was interpreted, structured, and validated by the magus, reflecting a complex interplay between shared labour and guiding authority.

Della Porta’s dedication to the broader diffusion of knowledge highlighted his wider goal: disseminating natural philosophy for the benefit of humanity and future generations (Della Porta 1611). To achieve this, he chose to publish Magia naturalis not only in Latin but also in the vernacular, entrusting this language with the final, definitive, and “new secrets”-enriched edition of his work. This deliberate use of the vernacular signalled a broader transformation in early seventeenth-century scientific practice, as the vernacular increasingly emerged as a legitimate medium to validate, communicate, and disseminate empirical findings, challenging the exclusive authority of Latin in scholarly discourse.

His pursuit was far from solitary; he actively consulted libraries, learned men, and artificers across France, Italy, and Spain. Della Porta emphasized his relentless personal efforts to “discover the secrets of Nature,” stating that he had diligently examined the “monuments of our ancestors.” Crucially, he outlined a truly extensive network of inquiry, detailing how he travelled to France, Italy, and Spain to consult with “all libraries, learned men, and artificers” to acquire truths they had “proved by their long experience.” He further maintained an active correspondence with those he could not visit, utilizing “entreaties, gifts, [and] commutations” to obtain their rare secrets (Della Porta 1589; Porta 1658, Preface to the Reader, s. p.).

This extensive network of inquiry underscores Della Porta’s practical engagement with a collaborative model of knowledge acquisition, emphasizing empirical validation and a broad collection of insights.

Crucially, this empirical and collaborative methodology was then elevated to a philosophical imperative. He explicitly rejected the idea that access to nature’s hidden truths should be restricted to a select few, aligning this open approach with a broader vision of scientific ethics and communal benefit. He powerfully linked knowledge dissemination to moral duty, declaring that the “most majestic wonders of nature are not to be concealed,” and that withholding these things from the world would bring the reproach of a “wicked man.” Echoing classical thought (via Cicero and Plato), he asserted that “we were not born from ourselves alone,” but have a duty to society. Therefore, he concluded, secrets long hidden by the “envy or ignorance of others” must be brought to light “without fraud, or deceit.” Della Porta 1589; Porta 1658, Preface to the Reader, s. p.). This commitment to disclosure, however, was subtly yet fundamentally tempered by the magus’s necessary discretion, which required protecting dangerous or misunderstood knowledge from the “profane” and ill-intentioned, an ethical imperative that complicates his celebration of openness.

Thus, Della Porta does more than simply lay bare his rigorous, collaborative methodology; he fundamentally establishes a profound ethical and societal framework for his scientific enterprise. By linking the pursuit of knowledge directly to a moral obligation to benefit humanity—a principle, as we’ve seen, that was already deeply rooted in the Renaissance culture of the Kingdom of Naples (exemplified by Ruscelli’s academy)—Della Porta advocated for scientific discovery to be treated as a public trust. His open approach represents a significant moment in the developing discourse on scientific communication, and, as Vincenzo Ferrone has argued, his legacy would later resonate even with the prophets of the Neapolitan Enlightenment (see Ferrone 1989, 35–51). Della Porta advocated for knowledge to be a shared inheritance, ultimately freed from the chains of envy or uncritical adherence to tradition, and instead offered openly for the collective good and the advancement of future generations. Yet, for this public dissemination to be achieved responsibly, scientific inquiry first had to undergo the necessary rigorous verification, an element that required—in line with the venatio program of his contemporaries—the maintenance of a margin of secrecy. This dual role of the magus, as both the ethical proponent of radical disclosure and the guardian of dangerous knowledge against misuse, defines the sophisticated epistemology of the Magia naturalis within the challenging context of the Counter-Reformation (see Eamon 1994; Valente 1999; Verardi 2018). Indeed, the very necessity of hiding his identity under the pseudonym Giovanni De Rosa when translating the Magia naturalis into the Italian vernacular is emblematic of this mixture of openness and necessary secrecy, mirroring the difficulties faced by science in a delicate period of profound transformation.

In this sophisticated structure of inquiry, the magus emerges as the philosophical coordinator and decisive moment of synthesis for collective knowledge, embodying philosophical rigor and coordination rather than control. His methodology, combining logic, collaborative empiricism, and a complex ethical framework of disclosure and secrecy, powerfully encapsulates the transitional epistemology inherent in the quest for a new understanding of nature.