In 1508, Johannes Trithemius, the Black Abbot, dedicated his Polygraphia , a treatise on writing in ciphers, to Emperor Maximilian I, personally handing over an elaborate autograph. Unlike the editio princeps , which was to be printed a decade later, the manuscript retains the arcane and mysterious tone of the bibliophile scholar’s earlier works on the subject. This book offers the first critical edition and translation of this first version, together with an extensive commentary illuminating the numerous obscure allusions, the impressive literary knowledge of its author, and the genesis of the mechanisms discussed.