In the other life, as mentioned [Sections 1388, 1396], one individual recognizes another’s character as soon as that other approaches, even if she or he says nothing. This experience reveals the fact that our inward reaches are somehow active (although we are unaware of it) and that their activity enables others to perceive what kind of spirit we are. I was able to see the truth of this by observing that the aura of this activity not only radiates far and wide but sometimes (when the Lord allows) makes itself perceptible in various ways.
In addition, I learned how we acquire these auras, which become so tangible in the other world. To put it in comprehensible terms, take the example of people who have formed an opinion of themselves as superior to others. They eventually develop the habit and the instinct, so to speak, of focusing on themselves whenever they see other people or talk to them, wherever they go. They do so consciously at first and then unconsciously, so that they themselves become blind to it. Still, the habit governs every one of their gestures and words, just as it governs every one of their feelings and thoughts. This is something we are capable of noticing in others. Such a trait is what creates an aura in the next life, and others perceive the aura, but no more often than the Lord allows.
The same is true with other attitudes as well. As a result, there are as many auras as there are moods and combinations of mood, which are countless. Our aura is like an image of ourselves projected outside us. In fact it is an image of everything inside us. What presents itself to view or to perception in the world of spirits, however, is only a general approximation. In heaven, on the other hand, our character is recognized in a more specific way. No one but the Lord, though, knows what we are like down to the smallest details.
from Secrets of Heaven, Volume 2, sections 1504, 1505