614. 14:2 And I heard a voice from heaven, like the voice of many waters. This symbolizes the Lord speaking through the new heaven with Divine truths.

A voice from heaven symbolizes an utterance or declaration coming from the Lord through heaven, for when a voice is heard from heaven, it comes from the Lord. Here it comes through the new heaven formed of Christians, meant by Mount Zion on which the Lamb was seen standing, and with him the one hundred and forty-four thousand (nos. 612[1-4], 613). Many waters symbolize Divine truths (no. 50).

The Lord is similarly depicted as speaking through heaven with Divine truths in the following places:

The Son of Man's voice was heard "as the sound of many waters" in Revelation 1:15. And the voice from the throne "as the sound of many waters" in Revelation 19:6. The voice of the God of Israel "like the sound of many waters" in Ezekiel 43:2.

The voice of Jehovah is over the waters..., Jehovah over many waters. (Psalms 29:3)

...the sound of (the cherubim's) wings, like the sound of many waters... (Ezekiel 1:24)

Cherubim symbolize the Word (no. 239), thus the Divine truth with which the Lord speaks.

In Exodus 9:23, 29, this signifies truths divine which enlighten and perfect people in heaven, but terrify people in hell. (Arcana Coelestia 7573)

In Psalm 29:3, this signifies the Word in its power. (Doctrine Regarding Sacred Scripture 18[4])

When the Lord speaks through the heaven, it descends into the lower spheres and is heard as thunder. As He speaks through the whole of heaven at once, the sound is called 'seven thunders' in Revelation 10. 'Seven' signifies all, everything, and wholeness. This is why 'thunder' signifies instruction and perception of truth, and in this instance, the revealing and manifestation of truth. A voice from heaven is heard as thunder when it comes from the Lord, which can be seen in John 12:28-30, Job 37:4-5, 2 Samuel 22:14, Revelation 14:2, and Psalms 81:8. 'Great thunder,' as in Revelation 14:2, signifies the divine good of divine love.

(References: Apocalypse Explained 10, 14 [2]; Apocalypse Revealed 472)