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)

9835. 'With the work of a designer' means a product of the understanding. This is clear from the meaning of 'a designer' as the power of understanding, dealt with in 9598, 9688, so that 'the work of a designer' means that which is a product of that power. 'A designer' (excogitator) means the power of understanding because thought (cogitatio) belongs to the understanding, even as love and affection belong to the will. In the internal sense 'a designer' and 'thought' have the same meaning; for in that sense no attention is paid to the person, only to the actual reality that is meant, and 'designer' carries the idea of a person. For the truth of this, see 5225, 5287, 5434, 8343, 8985, 9007. What 'a product of the understanding' means must be stated briefly. The subject at present is the Lord's spiritual kingdom, and this kingdom - so far as all truths and forms of good there are concerned - belongs to the understanding part of the mind, whereas things in the Lord's celestial kingdom belong to the will part. For there are two entities with which everything in all creation has connection, good and truth; and this is why in the human being there are two mental powers, will and understanding. The will exists for the sake of good, and the understanding for the sake of truth; for the will is the recipient of good, and the understanding that of truth.

[2] The situation in the heavens is similar. There two kingdoms exist, the celestial and the spiritual. The celestial kingdom exists to be a recipient of good and the spiritual kingdom to be a recipient of truth. And since the whole heaven corresponds to everything that exists with the human being, and heaven in the Lord's sight is consequently like one complete human being, this as well has the two powers of will and understanding, the will residing in the celestial kingdom and the understanding in the spiritual kingdom. Now because the spiritual kingdom was represented by Aaron's garments and heaven's power of understanding resides in this kingdom, 'the work of a designer' accordingly means the power of understanding.

The whole heaven, by virtue of the correspondence with every single thing that exists with the human being, is like one complete human being and is called the Grand Man, see the places referred to at the end of 9276. The forms of good and the truths present with those in the Lord's spiritual kingdom have been inscribed on the understanding part of their mind, but with those in His celestial kingdom on the will part, see the places referred to in 9277, 9596.