Trithemius informed his friend of the projected work whose first book would be entitled Steganography (in our day it would be called cryptography), “which, when published, will astonish everyone.” This first outline comprised four volumes (not five, as Klaus Arnold believes), the first two of which dealt with cryptography and writings in encaustic, the third of an accelerated method of learning a foreign language, and the fourth of cryptographical methods as well as occult subjects “which cannot be advanced in public.” Trithemius asserts, to be sure, that nothing he professes is transnatural, but on hearing him boast that according to his method the common man could master Latin in two hours, we are tempted to suspect that such a feat is impossible without the intervention of a very powerful spirit.
– Eros and Magic in the Renaissance (1987), p. 168