Arcana Coelestia #860
860. From these considerations it also becomes clear that all regeneration advances from evening to morning, as is mentioned six times in Genesis 1 where the regeneration of man is the subject. Here the evening is described in verses 2-3, the morning in verses 4-5. The present verse describes the first ray of light or the morning of this state as 'the tops of the mountains appearing'.
Three
The number three in the Bible represents completeness. That's why Jesus rose on the third day after the Crucifixion -- his transformation was complete. It's why Elijah stretched himself on the dead child three times, why Jonah was in the belly of the fish for three days, why the Lord called Samuel three times, and many more. It's also reflected in the fact that there are three levels of heaven, three levels of hell, three levels to human life and, ultimately, three aspects of the Lord Himself: Father, Son and Holy Spirit.