An inquiry may naturally here be made, why Moses mentions by name, "whales" only. But it is so, that the Scriptures in general make mention only of the greater fishes. The mention of "leviathan" and of "dragons" in the Book of Job, and in other places of the Scriptures is well known. It is certain however that all the large sea-monsters are called by the name, "whales;" some of which have wings as the dolphin, the king of fishes. Not however because it exceeds all other fishes in size. For the eagle, the king of birds, does not surpass all birds, nor is the lion, the king, larger than all other beasts.
I believe however the reason of this is that we might know that these huge bodies are really the glorious works of God, and that we might not through any terror at such awe-striking bulks, imagine that these stupendous animals were not works of God, but unreal monsters. These great facts of creation being thus established in our minds, it is easy to conclude, that as these enormous bodies were created by God, the lesser fishes, such as herrings, sprats, minnows, etc., were created also by him. Let him who would contemplate this more deeply read Job, Chap. 41. He will there plainly see in what lofty language the Holy Spirit, by means of the poet-author of that book, lauds that marvellous monster "leviathan," whose strength and confidence is such that he contemns even the force of arrows. Such descriptions open our eyes and encourage our faith to believe the more easily and firmly that God is able to preserve us also, who are so indescribably less in magnitude and strength.
A question here also raised concerning mice and doormice; whence and how they originate and are generated. For we find by experience that not even ships, which are perpetually swimming on the ocean, are free from mice, and no house can be thoroughly cleared of mice but that they will still be generated. The same inquiry may be instituted concerning flies. And also whither birds go in the time of autumn.
If you ask Aristotle concerning mice, his argument is that some animals are homoigena, "generated from a like kind," and others, heterogena, "generated from a different kind," and that mice are "heterogena," because mice, he says, are not generated from mice only, but from putrid matter; the putridity of which is consumed and gradually becomes a mouse.
If you ask by what power this generation is effected, Aristotle answers that the putrid humidity of this matter is cherished, generatively, by the heat of the sun; and that by this process a living animal is produced; just as we see the bluebottle fly generated from horse-manure. But this reasoning is far from satisfying me, for the sun warms all things, but generates nothing, unless God speak it into being by his divine power. Even supposing therefore that the mouse were generated from putrid matter, yet the mouse would be a creature of divine power.
The mouse is therefore a creature of the divine Word and power; and it is, as I believe of an aqueous nature. Were it not a creature of the divine Word and power, it would have no natural form nor would its species be preserved. Whereas it has a form the most beautiful, in its kind; legs of such exquisite symmetry, hair so smooth, as to make it evident that it was created for a certain order of creatures by the Word of God. In the mouse therefore we admire also the creature and the workmanship of God. And the same may as certainly be said of flies.
Concerning the disappearing of birds I have no certain knowledge. For it is not very likely that they retire into regions farther south. Indeed the miracle concerning swallows is known by experience, that they lie as dead in the waters during the winter, and revive at the approach of summer; which fact is indeed a great similitude and proof of our resurrection. For these are operations of the divine Majesty truly wonderful. Hence we see them, but we understand them not. And my belief is that although a single swallow may appear unseasonably, now and then, I doubt however whether it ever can be the case, such swallow is restored from its death-like state by God himself.
Unto the creation work of the fifth day therefore belong all crawling, creeping and flying creatures; and all other creatures which move in any way in the air or the water.
III. V. 21b and 22. And God saw that it was good. And God blessed them.
Why did not God pronounce the Word of blessing upon the above inanimate bodies of his creation also? In those cases he only said, that the bodies which he had created pleased him, but he did not bless them. But when he comes to the generation and propagation of living bodies, then he institutes a new mode of their increase and multiplication. Hence the sun and the stars, as we see, do not generate from themselves bodies like unto themselves. But herbs and trees have this blessing upon them, that they grow and bring forth fruit. Still there is nothing in them like unto this present blessing, pronounced by God upon the living bodies.