Giambattista Della Porta and Magia naturalis: the Secrets of Naples

In 1558 a young Neapolitan gentleman published a book that would be translated into many languages and read for more than a century: Magiae naturalis sive de miraculis rerum naturalium libri IIII. Giambattista Della Porta, born in 1535 into a wealthy family with estates at Vico Equense, was barely over twenty. His idea of magic was far from spirits and rituals: for him the magus was above all a curious observer, able to reproduce the wonders of nature.

A Magic without Demons

From the first pages Della Porta defines natural magic as the practical part of natural philosophy. The magus does not work miracles, but knows the sympathies and antipathies between things, that is, the affinities and aversions tradition attributed to plants, animals, stones and metals. By exploiting them he can obtain effects that seem prodigious to the layman, but which in reality follow the natural order established by God.

In this Della Porta connected himself to Ficino, Pico and Agrippa, but shifted the emphasis from speculation to experiment. His book gathers information from ancient authors such as Pliny and Theophrastus, from medieval treatises and from trials made personally or by friends. Much of that information proved false; some anticipated scientific observations that would be explored more deeply only later.

From Four Books to Twenty

In 1589 a new edition appeared in Naples, expanded to twenty books and thoroughly revised. Its subjects range from the generation of animals to the grafting of plants, from distillation to perfumes, from invisible writing to fireworks, from magnetism to optics. It is an encyclopaedia of the “secrets” of the age, those craft and natural techniques that circulated in collections of recipes and curiosities.

The book on optics is the best remembered. It describes the camera obscura fitted with a lens, able to project sharp images on a wall, and discusses the combined use of concave and convex lenses. This later led Della Porta to claim a kind of priority in the invention of the telescope, a claim historians judge exaggerated but not without some theoretical basis.

The Academy of Secrets and the Inquisition

Around 1560 Della Porta founded in Naples the Academia Secretorum Naturae, also called the Academy of Secrets. To be admitted, members had to present a piece of natural knowledge that was new and not yet published. The initiative attracted the attention of church authorities, who suspected illicit practices. Della Porta was summoned to Rome and the academy had to close, although the author continued to enjoy the protection of powerful prelates.

In the following years he published De humana physiognomonia, in 1586, in which he compared the features of the human face with those of animals in order to infer character, and he wrote numerous well-received comedies. In 1610 he joined the Accademia dei Lincei founded by Federico Cesi, the same academy that would welcome Galileo the following year.

Della Porta died in Naples in 1615. His work shows the moment when Renaissance natural magic was beginning to turn into experimental science. Between the world of Agrippa and that of Galileo, the Neapolitan gentleman represents a decisive transition, made of curiosity, domestic laboratories and a great passion for the wonders of nature.