Genesis 1:20

(20) Let the waters . . . in the open firmament.—The days of the second creative triad correspond to those of the first. Light was created on the first day, and on the fourth it was gathered into light-bearers; on the second day air and water were called into being, and on the fifth day they were peopled with life; lastly, on the third day the dry land appeared, and on the sixth day it became the home of animals and man.

Bring forth abundantly the moving creature that hath life.—Literally, let the waters swarm a swarm of living soul. But the word soul properly signifies “breath,” and thus, after the long pause of the fourth day, during which vegetation was advancing under the ripening effects of solar heat, we now hasten onward to another creative act, by which God called into being creatures which live by breathing. And as vegetation began with a green tinge upon the rocks, so doubtless animal life began in the most rudimentary manner, and advanced through animalcules and insects up to fish and reptiles. The main point noticed in the text as to the living things produced on this day is their fecundity. They are all those creatures which multiply in masses. It does not, however, follow that the highest forms of fish and reptiles were reached before the lowest form of land animal was created. All that we are taught is that the Infusoria and Ovipara preceded the Mammalia. As the most perfect trees may not have been produced till the Garden of Eden was planted, so the peacock may not have spread his gaudy plumes till the time was approaching when there would be human eyes capable of admiring his beauty.

And fowl that may fly.—Heb., and let fowl, or winged creatures, fly above the earth. It does not say that they were formed out of the water (comp. Genesis 2:19). Nor is it confined to birds, but includes all creatures that can wing their way in the air.

In the open firmament.—Literally, upon the face of the expanse of heaven—that is, in front of it, upon the lower surface of the atmosphere near to the earth.