The "midst" of something in the Bible represents the thing that is most central and most important to the spiritual state being described, the motivation that drives everything else. In general this will be something we love or feel, because at the core of things we are what we love; our loves define us.

(References: Apocalypse Revealed 44, 90, 268; Arcana Coelestia 2252, 2940, 10153, 10365, 10557, 10635, 10641)

2891. Those who have become spirits only recently torment themselves very much by trying to grasp the idea that no one is able to do good of himself, or to think what is true of himself, but that he does so from the Lord. For they believe that if that idea is true they would accordingly be like mere machines and have control of nothing at all; and that being so they would let hands hang down and allow themselves to be acted upon. But they are told that they ought by all means to think, to will, and to do good of themselves, and that in no other way could they have a heavenly proprium and heavenly freedom. But they are also told that they ought nevertheless to acknowledge that good and truth do not originate in themselves but in the Lord, and they are informed that such acknowledgement and indeed perception that this is so exists with all angels. And the more keenly they perceive that they are led by the Lord and so abide in Him the more they are in freedom.