Dante used angelology and astrology to classify the kinds of blessed and he was helped by Albertus Magnus' commentary on the De Caelesti Hierarchia the proof that Dante read Albertus' commentary is the prerogative he gives to the angels called Thrones. From neoplatonic Dionysian-eriugenian philosophy, the poet took the threefold structure of the universe, which implies a journey through each section. Another Dionysian debt is the use of the metaphor of the mirrors.