'Waters' particularly signify the spiritual parts of a person, or the intellectual aspects of faith, and also their opposites.

'The waters above the firmament,' as in Genesis 1:7, signify the knowledges in the internal self, and 'the waters beneath the firmament' signify the knowledges of the external self.

'Waters,' as in Ezekiel 47:9, refer to the New Jerusalem, and they signify spiritual things from a celestial origin.

'Many waters,' as in Revelation 17:1, signify truths of the Word adulterated. 'Waters' or 'rivers' signify spiritual, rational, or scientific things pertaining to truth.

'Waters … that go softly,' as in Isaiah 8:6-7, signify spiritual things, and 'waters … strong and many,' signify falsities.

'Waters,' as in Psalms 104:3, signify divine truths.

'Waters' signify truths in the natural self, and in the opposite sense, falsities.

'The waters were dried up from off the earth,' as in Genesis 8:7, signifies the apparent dissipation of falsities.

(Odkazy: Apocalypse Explained 17; Apocalypse Revealed 50; Genesis 8)

108. Verse 7. He that hath an ear let him hear what the Spirit saith unto the churches, signifies that he who understands should hearken to what Divine truth proceeding from the Lord teaches and says to those who are of His church. This is evident from the signification of "He that hath an ear let him hear," as being that he who understands should hearken, or obey (that to "hear" is to understand and to do, that is, to hearken, see above, n. 14; also from the signification of "the Spirit," here the Spirit of God, as being Divine truth proceeding from the Lord (See Arcana Coelestia 3704, 5307, 6788, 6982, 6993, 7004, 7499, 8302, 9199, 9228-9229, 9303, 9407, 9818, 9820, 10330); and from the signification of "churches," as being those who are in truths from good, or in faith from charity, that is, who are of the church, for no others are of the church. These words, namely, "He that hath an ear let him hear what the Spirit saith into the churches," are said to each of the churches (here to the church of Ephesus; afterwards to the church in Smyrna, verse 2:11; in Pergamum, verse 2:17; in Thyatira, verse 2:29; in Sardis, chapter Revelation 3:6; in Philadelphia, verse 3:13; and in Laodicea, verse 3:22), in order that everyone who is of the church may know that it is not knowing and understanding the truths and goods of faith, or doctrinals, or even the Word, that makes the church, but hearkening, that is, understanding and doing; for this is signified by the words "He that hath an ear let him hear what the Spirit saith unto the churches." Because this makes the church and forms heaven with man, and knowing and understanding, apart from doing, does not, therefore the Lord also uses the same words in several other places:

He that hath an ear to hear let him hear (as in Matthew 11:15; 12:43; Mark 4:9, 4:23; 7:16; Luke 8:8; 14:35).

In Revelation it is added, "what the Spirit saith unto the churches;" since by this is signified what Divine truth teaches and says to those who are of the church, or what is the same, what the Lord teaches and says, for all Divine truth proceeds from Him (See in the work on Heaven and Hell 13, 133, 137, 139); for this reason the Lord did not Himself say, "what the Spirit saith," because He who spoke was the Divine truth.

[2] That knowing and understanding Divine truths does not make the church and form heaven with man, but knowing, understanding, and doing, the Lord teaches plainly in many passages; as in Matthew:

He that heareth these words of Mine and doeth them, is likened unto a prudent man, but he that heareth and doeth them not, is likened unto a foolish man (Matthew 7:24, 26).

In the same:

He that was sown upon good land, this is he that heareth the Word, and taketh heed and thence beareth fruit (Matthew 13:23).

In Luke:

Everyone that cometh to Me and heareth My words, and doeth them, I will show to whom he is like. He is like a man building a house, who laid the foundation on a rock. But he that heareth and doeth not is like a man that built a house upon the earth, without a foundation (Luke 6:47-49).

In the same:

My mother and My brethren are they who hear the Word of God and do it (Luke 8:21);

and in many other places. In these passages, "hearing" signifies simply hearing, which is knowing and understanding. "Hearing," in common discourse, has this meaning when one is said "to hear" a thing; but it means both understanding and doing when it is said "give ear to," or "hearken to," also "listen to." Moreover, those who have separated life from faith are like those of whom the Lord speaks in Matthew:

Seeing they see not, and hearing they hear not, neither do they understand (Matthew 13:13-15; Ezekiel 12:2).