To gather, as in Genesis 6:21, refers to things gathered together in the memory of man. It also implies that good things and truths should be gathered together in man before he is regenerated. To gather together in a place to battle, as in Revelation 16:1, signifies the start of combat against truths in defense of falsities. The ancients were accustomed to say that, when anyone died, that he was gathered to his fathers, or to his people, and they understood that he actually came to his parents, his relations and kinsfolk in another life. 'To be gathered to his fathers' means that a person would join the spiritual community sharing similar good loves. 'To be gathered to his people' means that a person would join the spiritual community that holds same true ideas.

(References: Apocalypse Explained 16; Arcana Coelestia 679, Genesis 10, 25, 25:10)