‘Books of Secrets’ (Libri di Secreti or, more generically, ricettari) first flourished during the middle ages. They were technical, crafts-based ‘how-to-do it’ manuals, ‘secret’ because they were written in Latin and available only to the privileged few. With the advent of the printing press, vernacular editions started to appear—the first in Italian was the Opera Nuova intitolata Dificio di ricette in 1521 —and by the mid-sixteenth century secrets books were flooding off the presses. They tended to contain instructions for the making of medicines, recipes for preserving food, recipes pertaining to domestic management (such as making inks and removing stains), some for cosmetics and some ‘alchemical’ recipes, for refining chemicals. This mix was to remain characteristic of the genre, (although some dispensed with cookery and others with household management), which persisted well into the nineteenth century.
The importance of the genre lies in the fact that, as manuals for ‘domestic’ medicine with a huge circulation, they are central to the history of medicine and health. They reveal much about the kind of medical practices, approaches and ingredients adopted in the home amongst the general population, which may well have been quite different to those taught in Latin, at the university, or advocated by official pharmacopoeias. Close study enables us to track the dissemination of key developments in medical history, such as the shift from herbal to chemical medicine and from the ‘humoral’ to the ‘modern’ body. Italy was at the vanguard of medical developments during the Renaissance and although the genre soon became popular in other European countries, many of these were Italian texts in translation.
From: https://www.researchgate.net/publication/277246253_Italian_Book_of_Secrets_Database