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.

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

1304. That 'let us build ourselves a city and a tower' means that they fabricated a form of doctrine and of worship becomes clear from the meaning of 'a city' and from the meaning of 'a tower', dealt with in the paragraphs that follow this. The Church is such that when charity towards the neighbour departs and self-love takes its place, the doctrine of faith is of no account at all except insofar as it can be converted into worship of self. Nor do people consider that worship contains anything holy unless it exists for the sake of self, thus unless it is worship of self. This applies to all self-love. In fact a person who loves himself more than others not only hates everybody who is not subservient to him and shows no favour to them except when they have become subservient, but also, to the extent that he is not prevented, he plunges even into exalting himself above God. The fact that self-love is such when given free rein I have been shown in actual occurrences. These are the things meant by 'a city and a tower'. Self-love, and every desire springing from it, is of all things the filthiest and most unholy, and is very hell itself. From this anyone may deduce the nature of the worship that has such as this within it.