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.

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

Evening, a time when the light and heat are fading away, represents a state in which a person -- or a community of people -- is turning away from the Lord, with little desire left to be good and little knowledge left regarding what good is. Evening is often a time of judgment.

In Genesis 19:1, the evening signifies the visitation that comes before judgment. (Arcana Coelestia 2318)

In Genesis 30:16, this signifies the good or truth in a state of good, but in the obscurity that is characteristic of the natural. (Arcana Coelestia 3949)