The Book of Ptolemy is the geographical face of the Blue Book, the work Paulus of Alexandria sealed in Alexandria, as it showed itself in the gesta of 1300. It is one of the three pieces sought by the Florentines in that gesta, beside the Sword and the Stone (Holy Grail).
| Type | Object (book) |
| Stolen by | Marcos the Mage |
| Spanish entry | El Libro de Ptolomeo |
Nature
It is not a separate book. The Blue Book shows different faces to different readers: a treatise on the stars, an invocation, or a geography. In Florentine hands it opened its face of Ptolemy, and the Florentine chronicle remembers it as the Geography of Ptolemy. Its sealed, astrological face is the Eisagogika.
It mirrors Dante in reverse: where the Comedy descends through Hell, climbs Purgatory and reaches Paradise, this face makes the opposite, earthly journey, an excursion across the Earth, a geography of the whole world under the patronage of the Alexandrian who measured the sky and drew the earth.
It circulates in two bodies: printed versions with engraved plates, and rarer, more feared manuscript copies. It carries a poem in terza rima, Dante’s meter. Its knowledge outlived the gesta: centuries later it reappears almost intact in the work of a late Florentine, Francesco Berlinghieri, who put Ptolemy’s geography into Italian tercets.
History
It was kept in the library of Hell, from which it was stolen by Arsaces, called Marcos the Mage in Florence, the fisher-king who aged a thousand years between Alexandria and the forest. The same thief had, at another time, taken the same volume in its sealed face. Its trail is entangled with the sack of Alexandria by Aurelian, when the city of books burned.