 When seen in the context of the doctrine of physiognomics, it comes as no surprise that Porta authored a book on ciphers, as he believed himself endowed with a special ingenuity for decoding all forms of texts. Renaissance cryptographers in general had a penchant for mystery and the preternatural, as evident from Johannes Trithemius’s Steganography, for example. Trithemius, the Abbot of Sponheim, got in trouble with his ecclesiastical censors because he used a complex numerological series of demons’ names, arranged on Lullian wheels, for encryption (Arnold 1991). With their aura of mystery, ciphers thus qualified as a congenial topic for Porta’s general outlook as a popularizer of secrets and as inventor of marvels. De furtivis litterarum notis is apparently the first text on this topic that not only explained various ways to encrypt messages, but also gave detailed instructions on how to decipher coded messages (Strasser 2008). The art of cryptography had the advantage of being perhaps less wicked than necromancy, while still attracting the attention of powerful political patrons. For someone aspiring to be the adviser and protégé of one of the more powerful worldly rulers, it was therefore not an unwise choice to write such a book.