Dante is on the ledge of the envious. They are blind. They were turned inward upon themselves, loathing others for their success and laughing at other’s pain. They have repented and move toward the earthly paradise at the top of Mount Purgatory.
Envy kills fellowship. It is a sin of not loving our neighbor. Envy can lead to anger, wrath, to isolation.
The souls who speak to Dante repenting of their sin of envy, now love to help. They don’t do it out of duty but out of joy and love of others. In Purgatory, there is no longer sin. In Hell if Dante wasn’t sure if he were lost or going the right way, the souls would ignore him, talk about other things, especially themselves. Dante never getting an answer.
But in Purgatory, Dante is uncertain if he is going the correct way. But the souls assure him that he is going the right way. Envy will scoff or be silent out of derision for another. The envious, who no longer envy work together in their blindness and help one another to ascend together.