In the Word, “light” in the highest sense represents Divine Truth: knowledge, ideas, understanding that come to us from the Lord. In lesser degrees -- the light of a lamp, the light of the moon and so forth -- it represents lower levels of truth, ideas and understanding drawn from more earthly sources. Also, the sun in the Word represents the Lord, with its heat representing the divine love and its light representing the divine wisdom. That wisdom flows into our minds and enters our lives in the form of truth -- things we can know and ponder that lead us and help us to be good people. This connection between light and thought is one of many spiritual/natural relationships that's embedded in our common language. People “see the light” when they understand something; we try to “shed some light” by bringing new thoughts to a difficult question; people are “enlightened” when they get new information or a more complete understanding of something. And a light bulb in a cartoon represents an idea!

52. As long as someone is a spiritual man, the dominion over him runs from external man to internal man, as is said here, 'They will have dominion over the fish of the sea, over the birds of the air', and over the beasts, and over all the earth, and over every creeping thing that creeps on the earth'. When however he becomes celestial and does what is good out of love, then the dominion over him runs from internal man to external man. This is how the Lord describes Himself, and so simultaneously the celestial man, who is a likeness of Him, in David,

You have given him dominion over the works of Your hands; You have put all things under his feet, flocks and all cattle, and also the beasts of the field, the birds of the air, ¹ and the fish of the sea, and that crossing the paths of the seas. Psalms 8:6-8.

Here therefore the beasts are mentioned first, the birds next, and the fish of the sea after that, for the reason that the celestial man starts with love which resides in the will. With the spiritual man it is different. With him fish and birds, which have to do with the understanding, the domain of faith, come first, while beasts come afterwards.

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