'A plain' signifies the extremes of the Word regarding doctrine, and also the extremes of the church, or people in extremes of truths and goods. It also signifies good and truth in the natural self, because 'the people who dwell in plains,' or 'beneath mountains and hills' are in the extreme heaven. In Genesis 19:17, this signifies all doctrinal matters.

In Genesis 11:2, this signifies that their worship became more impure and profane. (Arcana Coelestia 1292)

In Jeremiah 21:13, this signifies the faith in which is no charity. (Arcana Coelestia 4715) Plain and valley signifies the ultimates of the Word. (Apocalypse Explained 411) Plain signifies good and truth in the natural man, because people in the First Heaven dwell in plain or valley. (Apocalypse Explained 449)

(Odkazy: Apocalypse Explained 400)

450. Among these twelve tribes, out of each of which twelve thousand are said to have been sealed, the tribe of Dan is not mentioned, but in its stead the tribe of Manasseh. The tribe of Dan is not mentioned because that tribe represented and signified such as are treated of in what now follows in this chapter, whom John thus describes, "After these things I saw, and behold a great multitude which no one could number, out of every nation and all tribes and peoples and tongues, standing before the throne and before the Lamb, clothed in white robes, and palms in their hands" (verse 9). For these are such as were not in the very truths of heaven and the church, but in the good of life according to the doctrinals of their religion, and these were for the most part not genuine truths but falsities, and yet these falsities were accepted by the Lord as truths, because such were in the good of life, and on account of this the falsities of their religion were not tainted with evil, but inclined to good. The others were taken in place of the tribe of Dan because the tribe of Dan was the last of the tribes, and therefore signified, in the Lord's kingdom, the ultimates in which those are who are in the good of life and of faith according to their religion in which there are no genuine truths. (Respecting the tribe of Dan see Arcana Coelestia 1710, 3920, 3923, 6396, 10335)