Continued from Comparing Dante and Milton, Part 1.
The positive way of Dante conforms to the high scholasticism of his day. Dante, particularly in the Paradiso, conforms to the way in which Thomas Aquinas values philosophy as a true and proper power to prepare the mind for grace (cf. Par. 4.118-32; 29.13-45). Subscribing to the scholastic presuppositions of his time, Dante firmly believes that theology builds on philosophy, and that revelation clarifies and fulfills reason. The role of theology as a the “queen of the sciences” supports a hierarchical view of reality deeply intertwined with the cosmology and poetic structure of the Comedy. Confirming the kataphatic or “positive” way, Dante depicts the universe as governed by the supreme divine intellect through a hierarchy of lesser intelligences who in turn enlighten the lower ones. The progressive hierarchy of hell-purgatory-heaven and the prominent role of mediating guides (Self > Virgil > Beatrice > Bernard > Mary) further confirm the affirmative way by which Dante perceives God and creation.
While Dante certainly believes that grace compliments nature, he also depicts nature and grace as formally distinct. The inability of the pagan Virgil to ascend into Paradise demonstrates that nature without grace cannot in fact prepare the soul for the beatific vision. Moreover, the presence in Limbo of ancient pagan worthies such as Homer, Plato, and Aristotle, alongside virtuous non-Christians such as Avicenna and Averroes, confirms that nature can attain a kind of natural beatitude, but it cannot ascend to the supernatural beatitude that Dante shall experience in the final canto of the Comedy.
See also Comparing Dante and Milton, Part 1.