Down, down they go until they reach the evil spirit's thighs, where, the centre of earth's gravity being reached, Virgil suddenly turns around and begins an upward climb with his burden.

Although Dante fully expects soon to behold Satan's head once more, he is amazed to discover they are climbing up his leg.

Then, through a chimney-like ascent, where the climbing demands all their strength, Dante and Virgil ascend toward the upper air.
Explaining they are about to emerge at the antipodes of the spot where they entered Hades, where they will behold the great Western Sea, Virgil adds they will find in its centre the Mount of Purgatory, constructed of the earth displaced by Satan's fall.

Thus, Dante and his leader return to the bright world, and, issuing from the dark passage in which they have been travelling, once more behold the stars! "By that hidden way My guide and I did enter, to return To the fair world: and heedless of repose We climb'd, he first, I following his steps, Till on our view the beautiful lights of heaven Dawn'd through a circular opening in the cave: Thence issuing we again beheld the stars." PURGATORY _Canto I._ About to sing of a region where human spirits are purged of their sins and prepared to enter heaven, Dante invokes the aid of the muses.

Then, gazing about him, he discovers he is in an atmosphere of sapphire hue, all the more lovely because of the contrast with the infernal gloom whence he has just emerged.