And God said,
Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
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Cyril of Jerusalem
For what fault have they to find with the vast creation of God, who out of the fluid nature of the waters formed the stable substance of the heavens? For God said, “Let there be a firmament in the midst of the waters.” God spoke once for all, and it stands fast, never failing.