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)

3648. There is also an influx from the Lord by way of heaven into objects of the vegetable kingdom, such as every kind of tree and its fruitings, and every kind of young plant and its increases. But for the constant activity of that which is spiritual from the Lord into the primitive forms existing within their seeds they would never start to vegetate and grow in so amazing a manner and sequence. But the forms there are such that they do not receive any life at all. It is from this influx that they have an image of what is eternal and infinite within them, as is evident from the fact that they contain a constant endeavour to reproduce their own genus and their own species and in so doing to live so to speak for ever and also to fill the whole world.

[2] This endeavour is inherent in every seed. Yet man attributes all those things that are so wondrous to natural forces themselves, not believing in any influx from the spiritual world since at heart he denies its existence. He does so even though he possibly knows that nothing can continue in existence apart from that which comes into existence, that is, he knows that a continuing in existence is a perpetual coming into existence, or what amounts to the same, reproduction is constant creation. Consequently the whole natural order is a theatre representative of the Lord's kingdom, see 3483. But these objects too, and their correspondence with the Grand Man, will in the Lord's Divine mercy be discussed elsewhere.