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.

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

10557. 'And his minister Joshua the son of Nun, a young man, did not move away from the midst of the tent' means Divine Truth ministering meantime in the holy things of the Church and worship in place of Moses. This is clear from the representation of 'Joshua, minister of Moses' as Divine Truth ministering in place of Moses (he is called 'the son of Nun' by virtue of what is true, and 'a young man' by virtue of what is good); and from the meaning of 'did not move away from the midst of the tent' as not ceasing meantime to minister in the holy things of the Church and worship. 'Not moving away' means not ceasing meantime, and 'the tent' means the holiness of the Word, the Church, and worship, dealt with above in 10545. In paragraph 10556 immediately above it has been stated that Moses now comes to represent the head of the Israelite nation. Consequently in order that the train of thought in the internal sense might not be broken, it happened that Joshua remained in the tent during Moses' absence. For 'Joshua' represents Divine Truth in respect of some function performed by it, such as Divine Truth engaged in conflict, 8595; Divine Truth engaged in contemplation and discernment, 10454; but here Divine Truth engaged in ministering, in the absence of Moses, which is why he is called Moses' 'minister'.