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.

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

41. Anything that is man's own has no life in it; and when depicted visually it looks like something hard as a bone and black. But anything that comes from the Lord does contain life. It has that which is spiritual and celestial within it, and when depicted visually it looks human and alive. It is perhaps incredible, but nevertheless absolutely true, that every expression, every idea, and every least thought of an angelic spirit is alive. In even the most detailed areas of his thought there is an affection that comes from the Lord, who is life itself. Consequently all that derives from the Lord has life within it, for it contains faith in Him, and is here meant by 'a living creature'. It then has the outward appearance of a body, meant here by that which is moving, or creeping. To man these matters remain arcana, but since the subject here is the living and moving creature, they ought at least to be mentioned here.