"Return unto thy science"

(Canto 6, line 106)

That is, the philosophy of Aristotle. Commentator Mazzoni explains that Dante here alludes to St. Thomas' commentary of Aristotle's "On the Soul", where a similar message is to be found. That is to say, after the Final Judgment, when souls have rejoined their bodies and therefore are again more perfect, the punishment of the punished will appear even worse, while the joy of those blessed will be even greater.