Arcana Coelestia #486
486. Verse 4 And the days of Man after he beget Seth were eight hundred years; and he beget sons and daughters.
'Days' means periods of time and states in general. 'Years' means periods of time and states in particular. 'Sons and daughters' means the truths and goods that they perceived.
Arcana Coelestia #491
491. The same things are meant by 'sons and daughters' in verses 4, 7, 10, 13, 16, 19, 26, 30, of this chapter, but the character of a Church determines that of its 'sons and daughters', or goods and truths. Here they are truths and goods that men perceived most clearly, for they have regard to the Most Ancient Church, the head and forefather of all other Churches that followed after it.