Della Porta, Isabella Cortese and Natural Magic in the Books of Secrets

After the success of Alessio Piemontese, sixteenth-century Italy saw a true season of books of secrets. Some were simple collections of recipes, others ambitious attempts to explain the phenomena of nature. At the centre of this production lay an ancient but renewed idea, that of natural magic: the conviction that nature concealed forces and correspondences that human beings could know and exploit without resorting to demons. Three authors show its different souls.

Giovan Battista Della Porta and the Magia naturalis

The Neapolitan Giovan Battista Della Porta published in 1558 the first version of the Magiae naturalis, in four books, written, according to tradition, when he was still very young. In 1589 a greatly enlarged edition in twenty books appeared, devoted to subjects such as magnets, lenses, perfumes, distillation, the transformation of metals, fireworks and optical illusions. For Della Porta natural magic was the practical part of natural philosophy.

The author founded in Naples an academy of secrets, in which members had to have discovered something new in order to be admitted. The initiative aroused the suspicion of the Inquisition, which investigated Della Porta and had the academy closed. Later he was welcomed into the Accademia dei Lincei, the same as Galileo's, and he also wrote a treatise on cryptography, the De furtivis literarum notis of 1563.

The Magia naturalis enjoyed a European circulation. It was reprinted many times and translated into several languages; the English version appeared in London in 1658 under the title Natural Magick. Some chapters, such as those on lenses and the camera obscura, were read with interest by students of optics, while others fed Della Porta's reputation as a magician, which followed him throughout his life.

The Secreti of Signora Isabella Cortese

In 1561 I secreti de la signora Isabella Cortese was published in Venice, a collection divided into books devoted to medicine, alchemy, cosmetics and the domestic arts. Nothing certain is known about the supposed author: she may have been a real person or a name chosen by the publisher to attract a female readership. The book nonetheless had numerous reprints until the seventeenth century.

The case of Isabella Cortese is interesting because it shows the importance of women as holders and recipients of practical knowledge. Many secrets concerned the care of the home, the body and the family, areas traditionally entrusted to women. The book gave printed form to knowledge that until then had been handed down mainly by word of mouth, from mother to daughter or among neighbours.

Leonardo Fioravanti, surgeon and populariser

The Bolognese Leonardo Fioravanti, a wandering surgeon and prolific author, published in Venice works such as the Capricci medicinali of 1561 and the Compendio dei secreti rationali of 1564. Fioravanti criticised academic medicine, extolled experience and promised spectacular remedies, which we now know to be without foundation. His works found readers throughout Europe and show the more commercial side of the genre.

These authors, so different from one another, shared a faith in the value of discovery and demonstration. Their books mix genuine curiosity, traditional beliefs and exaggerated promises, but it was precisely from this tangle that some of the methods of modern science were born. Studying them helps us understand how the boundary between magic and experiment shifted slowly, one book after another.