When spirits are in this state of their deeper concerns, then it is obvious what kind of people they really were in the world. They actually behave in accord with their own nature. People who were inwardly devoted to the good in the world then behave sanely and wisely, more wisely than when they were living in the world, in fact, because they have been freed from any connection with the body and therefore with the earthly things that darken and cover with a kind of cloud.
In contrast, people who were focused on evil in the world then behave foolishly and insanely, more insanely than when they were in the world, in fact, because they are in freedom and are no longer constrained. As long as they were living in the world, they were outwardly sensible, because this was how they imitated rational people. So when the outer layers are stripped off, their inner insanity is unveiled.
An evil person who outwardly pretends to be good can be compared to a brightly polished jar with a cover on, with all kinds of filth hidden inside, just as the Lord said: “You are like whitewashed sepulchers that look lovely on the outside but are inwardly full of the bones of the dead and all uncleanness” (Matthew 23:27).
from Heaven and Hell, Section 505