THE angels of any given heaven are not all together in one place, but are separated into larger and smaller communities depending on differences in the good effects of the love and faith they are engaged in. Angels engaged in similar activities form a single community. There is an infinite variety of good activities in heaven, and each individual angel is, so to speak, his or her own activity.
The distances between angelic communities in the heavens also vary as their activities vary, in general and in detail. This is because the only cause of distance in the spiritual world is the difference of the state of our more inward natures—in the heavens, then, differences in the state of love. When communities are very different, the distance between them is great; when the difference is slight, the distance is slight. Likeness makes for unity.
All the individuals in a single community are distanced from each other by the same principle. The better ones, that is, the ones who are more complete in goodness and therefore in love, wisdom, and intelligence, are in the center. Those who are less outstanding surround them at distances graded in proportion to their lessened perfection. It is like the way light decreases from a center toward a circumference. The ones who are in the middle are in the greatest light, while the ones who are toward the perimeter are in less and less.
from Heaven and Hell, Sections 41-43