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20 And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.
'To open,' as in Revelation 9, signifies communication and conjunction.
(References: Apocalypse Explained 537)
10 For the stars of the sky and its constellations will not give their light. The sun will be darkened in its going forth, and the moon will not cause its light to shine.