In Purgatory, everyone rushes about. Dante is warned by his teachers to hurry. The penitent souls rush towards the top of the mountain in their keenness for the gates of Heaven. This awareness and worry over time contrasts sharply with the never-ending tediousness of Hell found in Dante's Inferno. Like the human world, Purgatory operates on a normal time scale. This means that things change here, which – if you think about it – is the whole point of Purgatory. Men repent for their sins on earth. They work to improve themselves and make themselves morally better in God’s eyes. The passage of time allows these changes to happen.
The concept of time in each of the three realms (Hel, Purgatory, Heaven) dictates whether or not an individual can change his character in that place; while one cannot change in Hell, where damnation is eternal, he can change in Purgatory, where time runs as it does in the mortal world.