Midst
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)
Revelation 9:17-18
17
Thus I saw the horses in the vision, and those who sat on them, having breastplates of fiery red, hyacinth blue, and sulfur yellow; and the heads of lions. Out of their mouths proceed fire, smoke, and sulfur.
18
By these three plagues were one third of mankind killed: by the fire, the smoke, and the sulfur, which proceeded out of their mouths.