When Dante speaks of the “way of our life” in the first line of his poem, he is using a figure that was familiar in his day and has become a banality in ours. It is especially important in the Divine Comedy, however, for it helps set off that great work from the bizarre travel literature which preceded it in the Middle Ages, and which we have come to call the literature of “oltretomba.” Dante's journey is different, for it is not a dream and it is not his alone. It is an allegorical representation of a spiritual development: the cammino of man in this life. Dante's literary ancestor is Plato, and not Tnugdalus, and his Inferno, like Plato's cave, is the place where all men come to know themselves. St. Bonaventure was the medieval theorist who worked out the metaphor of the itinerarium mentis in great detail, but it remained for Dante to write the work which gave the metaphor substance and made great poetry from a figure of speech.