Fontana was a highly cultivated man who, after earning a medical degree in Padua, devoted himself to the study of optics, the art of memory, and pneumatics from Greek, Latin, and Arabic sources. The complex variety of his interests is evident in his Bellicorum instrumentorum liber, written between 1420 and 1449. The manuscript, now in Munich, contains a wealth of illustrations; many of the accompanying texts are in cipher. The document amply demonstrates not only Fontana's interest in military systems but his competence in hydraulics and precision mechanics. He applied these skills to build toys and produce special contraptions such as the blazing witch, the mechanical devil, and the resurrected skeleton.