…the Paradiso is very, very deep, so deep that I know I will struggle for the rest of my life to fully comprehend it. Dante knows this, and warns the reader in Canto II, at the outset of the journey across the ocean of Being toward full unity with God, thus:
Turn back if you would see your shores again.
Do not set forth upon the deep,
for, losing sight of me, you would be lost.
To experience God as Dante is about to, and as he is about to reveal to his readers, is to be forever changed. Be warned.
Though the lower parts of the journey through the Comedy are chiefly concerned with moral improvement, it would be a gross misreading of the text to construe it as a manual for How To Be Good. If you think that life in Christ is only about believing the right things and behaving in the correct way, you have a very shallow grasp of reality. This is why you can’t really understand the Inferno and the Purgatorio without seeing them through the lens of the Paradiso. (For that matter, the Comedy is Trinitarian: you can’t understand any one book without reference to the other two).
But to enter the text of Paradiso is to plunge into the mystic depths. The best guide I’ve found so far is one that is fairly difficult itself, but one that I also find indispensable: The Metaphysics of Dante’s Comedy, by Christian Moevs (pron. “mayvs”), a Notre Dame scholar who said incredibly nice things about my Dante book yesterday.