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.

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

2185. 'And set it before them' means that He so prepared Himself to receive. This becomes clear from the meaning of 'setting before them' in the internal sense, where the subject is the preparing of the rational to receive perception from the Divine, and so is clear without further explanation.