Arcana Coelestia #1020
1020. That these things are meant becomes clear from the fact that everything put together as history from Genesis 1 down to Eber in Chapter 11 means something different from what appears in the letter, and from the consideration that the historical narratives there are purely made-up history customary among the most ancient people. When attesting the truth of some matter they would say that 'Jehovah said it'. Here however 'God' is used because the subject is the spiritual Church. And they did the same when anything true was being, or had been, put into effect.
Flood
The flood was the end of the most ancient church, and the beginning of the ancient church. The flood which the serpent cast out of his mouth, as in Revelation 12:15, signifies reasonings in abundance grounded in fallacies and appearances. The flood, as in Genesis 7, not only signifies the temptations which the man of the church called Noah must undergo, before he could be regenerated, but likewise the desolation of people who could not be regenerated; both temptations and desolations are in the Word compared to floods, or inundations of waters. A flood signifies truths in abundance. “No more to destroy the earth”, signifies that such a deadly and suffocating persuasion as in the former church should exist no more.
(References: Apocalypse Revealed 564)