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)

1119. I have been shown by actually observing it how the internal breathing of the most ancient people flowed in a non-audible manner into a kind of external, and thus non-verbal, speech, which was perceived by another person in his interior man. They said that that breathing with them changed according to their state of love and faith in the Lord. They also stated the reason, namely that because they had had communication with heaven, it could not be otherwise. In fact they and the angels who accompanied them were breathing in unison. Angels have breathing to which internal breathing corresponds, and which with them changes in a similar way. Indeed when they encounter anything contrary to love and faith in the Lord their breathing is laboured, but when they are experiencing the happiness that accompanies love and faith, their breathing is full and free. Something similar to this also exists with every human being but in this case everything depends on the bodily and worldly loves and on a person's basic assumptions. When anything goes against these he experiences laboured breathing, but when it is in keeping with them his breathing is full and free. These observations however apply to external breathing. The subject of angels and their breathing will in the Lord's Divine mercy be dealt with later on.