"Before mine eyes did one present himself "

(Canto 1, line 62)

This is Virgil, or more correctly, his soul. Throughout the poem he is a symbol of intellect and philosophy and is trusted with the mission of guiding Dante through Hell and Purgatory on his way to eternal happiness. This illuminates a general idea: that man must rely on his intellect and philosophy to overcome his mistakes and sins and find a path to rebirth.