This is a key moment in this story. The beginning of John 1 explained that the Lord is perfect, infinite love which gave itself expression as divine truth. The duality of love and expression formed a template for humanity, which meant that the Lord’s duality made him the ultimate, divine human. It showed that the divine truth was the power of creation, and that the Lord shared that truth with humanity from the outset, so that people could receive His love and return it. But people kept turning away, and the Lord had to keep expressing his love in more and more external forms to maintain a connection.

By mentioning John the Baptist, the chapter showed that the Jews of the time still had the truth – the Lord’s Word – contained inside the rough-hewn images of the Old Testament. But they were so steeped in evil loves and false thinking that the connection to the Word – to the love within the Old Testament – was about to be snipped forever.

So the Word became flesh. The Lord passed the full expression of His love and His full humanity into physical flesh as Jesus. That way He could once again show the life within the existing Scriptures and could make His own life and His own words part of an expanded expression of truth for a new age of humanity. People could no longer see and feel the Lord’s love through the Old Testament, but they could see and feel it in the face and hands and words of Jesus.

The "glory" here expresses the blinding brilliance of that truth. The "Father" represents the Lord’s actual love itself, and being "begotten" means that the love was expressed in the form of truth. Being full of "truth" has a pretty obvious meaning, but "grace" means an affection, a love for what is true.

The Lord had to come. He had to let His humanity flow down into the flesh, into the most external of forms, because that was the only way we were going to see and embrace it.

(References: A Brief Explanation of the Teachings of the New Church 117; The Apocalypse Explained 1069 [3]; The Word 20; True Christian Religion 3, 85)

876. And worship him who made heaven and earth, and the sea, and the fountains of water. That this signifies acknowledgment and confession of Him from whom is the all of heaven and the church, and from whom is Divine truth, or the Word, is evident from the signification of worshipping, as denoting to acknowledge in heart, thus to confess and worship; concerning which see above (n. 790, 805, 821); and from the signification of heaven and earth, as denoting the internal and external of the church; concerning which also see above (n. 304, 752). The reason why heaven and the church are signified is, that the internal of the church within man is heaven; for it is in conjunction with the angels, because it makes one with them; for, as said above, man's internal is formed to the idea and image of heaven; but his external, to the idea and image of the world. However, the church within man, while he lives in the world, is in his Natural, which is his external; but then it is the church within man in his Natural or external, only when the internal is opened; for the church cannot exist within any one unless he has heaven within, whence enlightenment and influx from the Lord may pass into the Natural or external which is beneath. The same is also evident from the signification of the sea, as denoting Divine truth in ultimates, thus the Word in the letter, this being Divine truth in ultimates. The reason why the sea has such a signification is, that seas, as it were, appear in the ultimates of heaven. For it is the Divine truth proceeding from the Lord that forms the heavens and all things therein. The higher heavens appear to be in an ethereal atmosphere; the lower in an aerial atmosphere, and the lowest in a watery atmosphere; and this atmosphere appears like a sea to the eyes of those who stand afar off, but not to those who dwell there. Those who dwell there, are in the ultimates of Divine truth, which is such as the Word is in the sense of the letter. Hence it is that this is signified by the sea; but more may be seen above upon this subject (n. 275, 342, 511, 600).

The reason why the sea here signifies the Word in the letter is, that it is said the sea and the fountains of waters; and fountains of waters signify more interior Divine truth, such as is the Word in the spiritual sense. That a fountain of water has this signification is evident from the passages adduced from the Word and explained above (n. 483). That fountains of waters signify Divine truths from the Word is evident from this, that heaven and earth signify the internal and external of the church; and both are formed by Divine truth or the Word, as is said in John (1:1, 2, 14). The internal of the church [is formed] by means of Divine truth spiritual, and the external by Divine truth natural. Therefore fountains of waters are also here mentioned among the things made by the Lord.

[2] From these and many other things, it is evident how the spiritual ideas of angels differ from the natural ideas of men. The angels, whose ideas are spiritual, by worshipping Him who made heaven and earth, the sea, and the fountains of waters, understand nothing but the acknowledgment and confession of the Lord, from whom is the all of heaven and the church; and from whom proceeds Divine truth, or the Word in the natural and spiritual senses. The reason why the angels thus understand these words is, that the heavens in which they are, and which appear to the eye entirely like our earth, but full of gardens, flower-beds, and shrubberies, are not permanent like the lands on our globe, but come into existence momentarily altogether, according to the reception of Divine truth by the angels. Therefore also the aspect of all things there is changed, as the state of reception is changed, and consequently the state of their intelligence and wisdom; thus, according to the states of the church within them, in such a way that so far as they have the church in them, so also all things exist correspondently before their eyes. When therefore the heavens and earth are mentioned, they cannot but have an idea of the church, because they derive all things therefrom. But men cannot have that spiritual idea when heaven and earth are mentioned, because they are ignorant of such things; but they have a natural idea, which is according to the sight of their eyes. For they see the permanent heaven and earth, which are not changed according to the reception of Divine truth, and thence of the church, as in the angelic heavens. By heaven, therefore, they understand nothing else but the visible heaven, and by earth, nothing else but the inhabited earth.

[3] The state of heaven and earth according to the state of the church was represented among the sons of Israel, by the face of the land of Canaan, where they dwelt, being changed according to the states of the church among them, only, however, as to the produce, that is, of the harvest, of the oil, the vine, the fruits, and as to the rains. But this was the case because all things with them were representative of heavenly things. This is why it is so often said in the Word, that the land should give its produce, if they would keep the statutes and do them. But the case is different at this day, now that the interior things of the church have been opened by the Lord, and externals, which were representative of the interiors, have ceased.

From these things it is also evident what a difference there is between the ideas of angels and the ideas of men, concerning the new heaven and the new earth. For the angels, from their ideas, perceive the destruction of the heavens and the earths in the spiritual world; but men, the destruction of the heavens and the earth in the natural world. The heavens and the earths in the spiritual world, upon which were those who had lived a moral life in externals, and not also a spiritual life from internals, have also perished, according to the predictions. But of these things more may be seen in the small work concerning the Last Judgment.