Arcana Coelestia #3926
3926. 'A second son to Jacob' means a second general truth. This is clear from the meaning of 'son' as truth, dealt with in 489, 491, 533, 1147, a general truth being meant at this point, as is clear from what has been stated and shown above concerning the twelve sons of Jacob and concerning the twelve tribes named after them; that is to say, the general aspects of the Church, and consequently the general aspects of faith and love, or of truth and good, are meant and represented by those sons. They also mean in the contrary sense every general aspect of that which is not faith or love, that is, every aspect of falsity and evil, as will be evident from what is said further on.
Arcana Coelestia #533
533. Since nothing further is mentioned about Lamech apart from the fact that be beget sons and daughters, who are the conceptions and births of such a Church, there is no need to pause any longer over him. What these births, or sons and daughters, were, becomes clear from the Church, for the character of a Church determines that of its offspring. Both those Churches called Methuselah and Lamech breathed their last just before the flood.