966. And it became blood as of one dead. That this signified that all were falsified, is evident from the signification of blood, as denoting Divine truth; and, in the opposite sense, Divine truth falsified (concerning which see n. 30, 328, 329, 476, 748). In this case, therefore, that all the knowledges of truth from the Word were falsified. The knowledges of truth from the Word are the truths of the sense of the letter, or the truths in the Word for the natural man, which also are Divine truths. These altogether falsified are signified by the sea becoming blood, as of one dead.
The Divine truths of the sense of the letter of the Word are said to be falsified, when they are perverted even to the destruction of interior Divine truth, or of Divine truth in the heavens. They then also appear in the heavens with man as the blood of one dead. That those who separate faith from the goods of life falsify the Word has been often shown above; and it is of such that these things are said, as is evident from the second verse of this chapter.
Concerning the Fourth Precept of the Decalogue, that parents are to be honoured.
This precept also was given, because the honour of parents represented and thence signified love to the Lord, and love towards the church. For father, in the heavenly sense, or the heavenly Father, is the Lord; and mother, in the heavenly sense, or the heavenly mother, is the church. Honour signifies the good of love; and length of days, which is the consequence, signifies the felicity of life eternal. This precept is thus understood in heaven, where no other father is known but the Lord, and no other mother but the Lord's kingdom, which is also the church. For the Lord gives life from Himself, and by the church He gives spiritual nourishment. That in the heavenly sense of this precept, not any father in the world is meant, or indeed to be named, while man is in a heavenly idea, the Lord teaches in Matthew:
"Call no one your father on earth; for one is your Father, who is in the heavens" (xxiii. 9).
That Father signifies the Lord as to Divine Good may be seen above (n. 32, 200, 254, 297). That mother signifies the Lord's kingdom, the church, and Divine truth may be seen in Arcana Coelestia (n. 289, 2691, 2717, 3703, 5580, 8897). That length of days signifies the felicity of eternal life, n. 8898 in the same work: and that honour signifies the good of love, n. 8897 there, and above, n. 288, 345.
From these things it is now evident that the third and fourth precepts involve mysteries concerning the Lord; that is, the acknowledgment and confession of His Divine, and the worship of Him from the good of love.