 Comparison of the 1510 dedication copy, sent by Agrippa to Trithemius (MS Würzburg, M.ch.q.50), with the printed final edition (Cologne 1533), reveals the careful and thorough revision and enlargement to which the first draft was subjected. The book doubled in length, and fresh ideas and references were included. In updating the text, Agrippa mostly drew on works consistent with the sources he had already used in drafting the initial version. Between 1510 and 1533, he had studied a number of texts which he had previously been unaware of or neglected (Ficino’s commentaries on Plato and on Plotinus; Giovanni Pico’s Conclusiones, Heptaplus, and Disputationes adversus astrologiam divinatricem; Lodovico Lazzarelli’s Crater Hermetis; and Gianfrancesco Pico’s De rerum praenotione) or which had been published in the meantime (some of Erasmus’ writings; Paulus Ricius’ commentaries on Hebrew writings; Reuchlin’s De arte cabalistica; and Francesco Giorgio’s De harmonia mundi). Agrippa’s vast exploration of books allowed him to re-orient his youthful project, providing a definitive justification of his aim to restore in full the religious, cognitive, and practical scope of ancient magic. This “reformed magic” (magia reformata) would not only guarantee to the magus mastery over nature and the ability to attract astral and angelic virtues, but would also assure his ascent to the First Principle.