 The Magia Naturalis is, unsurprisingly, dedicated to this important patron. Porta presented Philip II with another book on ciphers (De furtivis litterarum notis vulgo de ziferis libri IV 1563), followed by L’arte del ricordare (1566), a treatise on the art of memory (a Latin version appeared in 1602 under the title Ars reminsicendi). In 1579 and during the following years, Porta was repeatedly invited to Rome by Cardinal Luigi D’Este (1538–1586), ostensibly to pursue his research into the secrets of nature, but perhaps more importantly to enjoy some protection in his household during his trial before the inquisition (Perfetti 2001). 1580 found Porta overseeing the construction of a parabolic mirror in Venice, where he met Paolo Sarpi (1552–1623) (Reeves 2008).