Why the portal to the Good Life can be hard to find.
Here is the opening of Canto X in Purgatory:
Poi fummo dentro al soglio de la porta
che ‘l mal amor de l’anime disusa,
perché fa parer dritta la via torta
Literally: Then we were inside the threshold of the gate, that bad loves of the soul leaves in “disuse”, because they make the twisted path already seem right.
So Dante makes a big point in the opening tercet here: many people will never start the process of correcting internal distortions and twisted apprehensions of the world – not because of avoidance or reluctance to admit this, but because everything will seem fine. The twisted filters on the world are thus not like the “funny mirrors” where you clearly can see the misrepresentation of reality, but they are largely not detectable in themselves. The twisted road will seem straight.
Meaning: introspection for “flaws” is thus partly impossible to do directly. Aiming for the Good and for Virtue, in Humility, and starting a process, is what will heal and clear up the perceptions and experience of the world. That, and finding a good guide.