'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.

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

7877. 'And I will see the blood' means the discernment of that truth by those who inflict damnation. This is clear from the meaning of 'seeing' as understanding and discerning, dealt with in 2150, 2325, 2807, 3764, 4403-4421, 4567, 4723, 5400 (its being the discernment by those who inflict damnation is shown in what follows); and from the meaning of 'the blood' as truth that belongs to the good of innocence, as above in 7846.

[2] What truth belonging to the good of innocence is must be stated. The good of innocence is the good of love to the Lord; for those governed by this love have innocence within them. This explains why those who are in the inmost or third heaven, being governed by love to the Lord, possess more innocence than all others. Because of their innocence those who are there look to others like young children, and yet they are the wisest of all in heaven, see 2306; for innocence resides within wisdom, 2305, 3495, 4797. The truth belonging to the good of innocence which exists with them is not the truth of faith but the good of charity. Those in the third heaven do not know what faith is, nor consequently what the truth of faith is; for they perceive intuitively the truth that composes faith, and in perceiving it intuitively know immediately that it is indeed the truth. They never engage in reasoning about whether it is such, let alone argue with one another about it. What is perceived in that intuitive way does not then come to be acquired knowledge. It is different with spiritual angels in the second heaven. The truth of faith leads them to the good of charity. They do therefore engage in reasoning about whether it is the truth or not, since they have no intuitive perception of whether it is or not. Truths then become knowledge they have acquired and are called matters of doctrine composing faith.

[3] For more about those in the inmost or third heaven, about their state being such that they perceive intuitively what the truth of faith is and do not therefore add it to their acquired knowledge, see 202, 337, 2715, 2718, 3246, 4448.

Why it is that Jehovah's words 'I will see', thus something said about Himself, mean discernment by those who inflict damnation, that is, by spirits from hell, may become evident from what has been shown before about the attribution of evil to Jehovah or the Lord, though in fact no evil at all comes from Him but from hell, see 2447, 6071, 6991, 6997, 7533, 7632, 7643. Evil which is permitted to exist seems to come from Him who permits it, since He is able to remove it. That is how it is here when it says that the firstborn of the Egyptians were put to death. It is attributed to Jehovah, for it says in verses 12 and 29,

I will go through the land of Egypt on that night, and will strike all the firstborn in the land of Egypt.

And it happened at midnight, that Jehovah struck all the firstborn in the land of Egypt, from Pharaoh's firstborn who was to sit on his throne, even to the firstborn of the prisoner who was in the dungeon.

Yet in the present verse the one to do this is called 'the destroyer',

The blood will be a sign for you on the houses where you are; and I will see the blood and will pass you by, and the plague will not be on you for the destroyer.

[4] It is similar with the vastation undergone by the evil in the next life, their damnation, and their being cast into hell, which are meant in the internal sense by the plagues, the death of the firstborn, and their being drowned in the Sea Suph. Jehovah or the Lord does not subject anyone to vastation, still less damn or cast into hell. Rather an evil spirit himself is the one who does it to himself, that is, the evil within him does it. This then is why 'I will see the blood' means a discernment by those who inflict damnation.

[5] As regards permission, it is impossible to state briefly the nature of it since a very large number of arcana are involved in it. When the wicked suffer damnation and torment the Lord's permission is not like that of one who desires what happens to them. It is like that of one who does not desire it yet cannot help them because His end in view, which is the salvation of the entire human race, is urgent and prevents Him from helping. For if He were to help them, that would be doing ill, which is completely contrary to the Divine. But more on these matters will in the Lord's Divine mercy be stated elsewhere.