Two episodes frame Trithemius better than the cipher book. The first is a forgery. To give the abbey of Sponheim and the German nation a deep past, he cited a chronicler named Hunibald, supposedly writing near the time of the Franks' Trojan origins, and wove from him a circumstantial early history that impressed the emperor Maximilian himself. No Hunibald manuscript has ever existed; when pressed to produce it, Trithemius could not, and his reputation among humanist historians never recovered.
The scholar who made Sponheim's library one of the wonders of Germany, roughly two thousand volumes assembled on an abbot's income, was also willing to manufacture the sources his shelves lacked. The second episode is a visit. In 1510 the young Heinrich Cornelius Agrippa came to him and showed him the draft of De occulta philosophia, the book that would organise Renaissance magic for a century. Trithemius read it quickly, approved, and sent the famous covering letter of advice: communicate vulgar secrets to vulgar friends, but higher secrets only to higher friends, speak of things public publicly and of exalted things secretly. Agrippa printed the letter with the book, and the abbot's rule of discretion became part of the charter of the Western esoteric tradition: learned magic as something to be written, but written guardedly, for the few. Forger, librarian, cryptographer and cautious patron, he taught the occult its manners.