It is well known that, in both the Monas hieroglyphica and the Mathematicall praeface, Dee drew a part of his inspiration from Pico della Mirandola’s works. However, the nature and extent of Dee’s borrowings has not yet been studied. In fact, the only work of Pico really read and used by Dee was the 900 conclusions, where he found the conception of ‘formal numbers’: that is, mystical numbers carrying magical and divinatory powers. This is very important, since Dee sees these numbers as the very instruments of ‘the law of Creation.’ Pico also played a major part in the foundation of Christian cabala: in this field, his influence on Dee was mainly indirect, given that Dee—in the wake of Geofroy Tory—extended to Greek and Latin the magical and mystical properties which Pico considered as an exclusive property of the Hebrew language. Thus, Dee transforms what he calls ‘vulgar cabala’—the part of cabala that deals with language—from a christianised Jewish cabala into a truly catholic cabala. But for Dee, this is only the lower sort of cabala: above it lies ‘real cabala’, that is, the art of transmuting any physical or spiritual body into another. ‘Vulgar’ magicians and alchemists fail to achieve their aim because they do not possess the mastery of this discipline. Dee took from Pico the notion that cabala is superior to magic, and that the latter cannot be successful unless supported by ‘the work of cabala.’ Finally, Dee’s conception of the ‘metamorphosis’ of the soul taking place between the ‘horizons’ of time and eternity is derived not only from Pico, but also from Thomas Aquinas’s Summa contra Gentiles.