'To open,' as in Revelation 9, signifies communication and conjunction.

(References: Apocalypse Explained 537)

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'.