I want to know the answer to the following question:
In which of Dante's works was Virgil a guide through Hell and Purgatory?
All the background I'm provided with is that "Dante also mentions Virgil in De vulgari eloquentia, along with Ovid, Lucan and Statius, as one of the four regulati poetae (ii, vi, 7).". Is that enough to answer the question?