931. Verse 2 (Revelation 15:2). And I saw as it were a glassy sea mingled with fire, signifies the generals of truth in the Word, transparent from spiritual truths, which are from the good of love. This is evident from the signification of "a glassy sea," as being generals of truth transparent from spiritual truths (See above, n. 275); also from the signification of "fire," as being the good of love (See n. 68, 496, 504, 916). It shall be told here briefly why "a glassy sea" signifies the generals of truth in the Word transparent from spiritual truths. The "sea" signifies truths in general, because "waters, fountains, and rivers," signify truths from which intelligence is derived, and the sea is their general receptacle. Truths in general, or the generals of truth, are such truths as are in the sense of the letter of the Word, and the sense of the letter of the Word is natural, and everything natural is a general receptacle of spiritual things. For nothing in the nature of the world, or nothing natural, is possible that does not exist from the spiritual; for the natural is formed from the spiritual, as an effect out of its effecting cause. And as thousands of things that are spiritual effect and form one natural thing, so this one, as it is the containant of the thousands, is a general thing.

[2] Such also is the Word in the sense of the letter in its relation to the Word in the spiritual sense; and as the spiritual sense of the Word is in the natural sense, and in it shines through before the angels, so the Word as to the generals of truth transparent from spiritual truths is signified by "the glassy sea." "Glassy sea" has the same signification elsewhere in Revelation:

And in sight of the throne a glassy sea like crystal (Revelation 4:6).

Also:

The city New Jerusalem, as well as the street of the city, appeared like pure gold, similar to transparent glass (Revelation 21:18, 21).

For that "city" signifies the doctrine of the church, and "street" the truth of that doctrine; and the truths of that doctrine, because they are genuine truths, derive their light and their transparency from spiritual truths. It is this transparency that is signified by "glass" and by "crystal":

Also over the heads of the cherubim a firmament was seen like the appearance of a wonderful crystal (Ezekiel 1:22).

This signifies the spiritual Divine in heaven. That "the glassy sea" signifies the Word in the sense of the letter transparent from its spiritual sense can be seen also from the fact that near it were seen "them that had the victory over the beast;" and these signify those who have not falsified the Word, and have not extinguished thereby the light of the spiritual sense.