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)

233. Around the throne were twenty-four thrones, and on the thrones I saw twenty-four elders sitting. (4:4) This symbolizes the organization of everything in heaven for the Last Judgment.

Someone unacquainted with the spiritual meaning of the Word and at the same time the genuine truths of the church may believe that when the time of the Last Judgment comes, the Lord will sit upon a throne, and will be surrounded by other judges, also on thrones. But someone who is acquainted with the Word's spiritual meaning and at the same time the church's genuine truths knows that the Lord will not then sit upon a throne, nor be surrounded by other judges - indeed, that neither will the Lord judge anyone to hell, but that He will occasion the Word to judge everyone, under His oversight to ensure that everything proceeds in accordance with justice. The Lord in fact says,

...the Father judges no one, but has committed all judgment to the Son... ...He has given Him authority to execute judgment, because He is the Son of Man. (John 5:22, 27)

[2] But elsewhere He says,

I did not come to judge the world but to save the world... The Word that I have spoken will judge him in the last day. (John 12:47-48)

These two statements are in harmony when one knows that the Son of Man is the Lord in relation to the Word (see no. 44 above). Consequently it is the Word that will judge, under the Lord's oversight.

To be shown that the twelve tribes of Israel and their elders symbolize all people who are part of the Lord's church in heaven and on earth, and in an abstract sense all the truths and goods in it, see nos. 251, 349, 369, 808. That the like is meant by apostles, nos. 79, 790, 903.

It is apparent from this what the symbolic meaning is of these words of the Lord:

Jesus said to (His disciples), ."..when the Son of Man sits on the throne of His glory, you who have followed Me will also sit on twelve thrones, judging the twelve tribes of Israel." (Matthew 19:28, cf. Luke 22:30)

The number twelve symbolizes all, and it is predicated of the truths and goods of heaven and the church (no. 348). So, too, the number twenty-four. Therefore the twelve apostles and the twenty-four elders symbolize all the constituents of the church, and the twelve disciples, as also the twenty-four thrones, symbolize all judgment. Who cannot understand that the apostles and elders are not going to judge, and are unable to do so?

From this it can now be seen why thrones and elders are mentioned where the subject is judgment, as also in Isaiah:

Jehovah will enter into judgment with the elders of His people... (Isaiah 3:14)

In the book of Psalms:

Jerusalem is built...(and) to it the tribes go up... ...thrones are set there for judgment... (Psalms 122:3-5)

And in the book of Revelation:

I saw thrones, and they sat on them, and judgment was turned over to them. (Revelation 20:4)