A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
gen 1:1THE CREATION OF HEAVEN AND EARTH. (Gen 1:1-2)
In the beginning--a period of remote and unknown antiquity, hid in the depths of eternal ages; and so the phrase is used in Pro 8:22-23.
God--the name of the Supreme Being, signifying in Hebrew, "Strong," "Mighty." It is expressive of omnipotent power; and by its use here in the plural form, is obscurely taught at the opening of the Bible, a doctrine clearly revealed in other parts of it, namely, that though God is one, there is a plurality of persons in the Godhead--Father, Son, and Spirit, who were engaged in the creative work (Pro 8:27; Joh 1:3, Joh 1:10; Eph 3:9; Heb 1:2; Job 26:13).
created--not formed from any pre-existing materials, but made out of nothing.
the heaven and the earth--the universe. This first verse is a general introduction to the inspired volume, declaring the great and important truth that all things had a beginning; that nothing throughout the wide extent of nature existed from eternity, originated by chance, or from the skill of any inferior agent; but that the whole universe was produced by the creative power of God (Act 17:24; Rom 11:36). After this preface, the narrative is confined to the earth.
gen 1:2the earth was without form and void--or in "confusion and emptiness," as the words are rendered in Isa 34:11. This globe, at some undescribed period, having been convulsed and broken up, was a dark and watery waste for ages perhaps, till out of this chaotic state, the present fabric of the world was made to arise.
the Spirit of God moved--literally, continued brooding over it, as a fowl does, when hatching eggs. The immediate agency of the Spirit, by working on the dead and discordant elements, combined, arranged, and ripened them into a state adapted for being the scene of a new creation. The account of this new creation properly begins at the end of this second verse; and the details of the process are described in the natural way an onlooker would have done, who beheld the changes that successively took place.
gen 1:3THE FIRST DAY. (Gen 1:3-5)
God said--This phrase, which occurs so repeatedly in the account means: willed, decreed, appointed; and the determining will of God was followed in every instance by an immediate result. Whether the sun was created at the same time with, or long before, the earth, the dense accumulation of fogs and vapors which enveloped the chaos had covered the globe with a settled gloom. But by the command of God, light was rendered visible; the thick murky clouds were dispersed, broken, or rarefied, and light diffused over the expanse of waters. The effect is described in the name "day," which in Hebrew signifies "warmth," "heat"; while the name "night" signifies a "rolling up," as night wraps all things in a shady mantle.
gen 1:4divided the light from darkness--refers to the alternation or succession of the one to the other, produced by the daily revolution of the earth round its axis.
gen 1:5first day--a natural day, as the mention of its two parts clearly determines; and Moses reckons, according to Oriental usage, from sunset to sunset, saying not day and night as we do, but evening and morning.
gen 1:6SECOND DAY. (Gen 1:6-8)
firmament--an expanse--a beating out as a plate of metal: a name given to the atmosphere from its appearing to an observer to be the vault of heaven, supporting the weight of the watery clouds. By the creation of an atmosphere, the lighter parts of the waters which overspread the earth's surface were drawn up and suspended in the visible heavens, while the larger and heavier mass remained below. The air was thus "in the midst of the waters," that is, separated them; and this being the apparent use of it, is the only one mentioned, although the atmosphere serves other uses, as a medium of life and light.
gen 1:9THIRD DAY. (Gen 1:9-13)
let the waters under the heaven be gathered together unto one place--The world was to be rendered a terraqueous globe, and this was effected by a volcanic convulsion on its surface, the upheaving of some parts, the sinking of others, and the formation of vast hollows, into which the waters impetuously rushed, as is graphically described (Psa 104:6-9) [HITCHCOCK]. Thus a large part of the earth was left "dry land," and thus were formed oceans, seas, lakes, and rivers which, though each having its own bed, or channel, are all connected with the sea (Job 38:10; Ecc 1:7).
gen 1:11let the earth bring forth--The bare soil was clothed with verdure, and it is noticeable that the trees, plants, and grasses--the three great divisions of the vegetable kingdom here mentioned--were not called into existence in the same way as the light and the air; they were made to grow, and they grew as they do still out of the ground--not, however, by the slow process of vegetation, but through the divine power, without rain, dew, or any process of labor--sprouting up and flourishing in a single day.
gen 1:14FOURTH DAY. (Gen 1:14-19)
let there be lights in the firmament--The atmosphere being completely purified, the sun, moon, and stars were for the first time unveiled in all their glory in the cloudless sky; and they are described as "in the firmament" which to the eye they appear to be, though we know they are really at vast distances from it.
gen 1:16two great lights--In consequence of the day being reckoned as commencing at sunset--the moon, which would be seen first in the horizon, would appear "a great light," compared with the little twinkling stars; while its pale benign radiance would be eclipsed by the dazzling splendor of the sun; when his resplendent orb rose in the morning and gradually attained its meridian blaze of glory, it would appear "the greater light" that ruled the day. Both these lights may be said to be "made" on the fourth day--not created, indeed, for it is a different word that is here used, but constituted, appointed to the important and necessary office of serving as luminaries to the world, and regulating by their motions and their influence the progress and divisions of time.
gen 1:20FIFTH DAY. The signs of animal life appeared in the waters and in the air. (Gen 1:20-23)
moving creature--all oviparous animals, both among the finny and the feathery tribes--remarkable for their rapid and prodigious increase.
fowl--means every flying thing: The word rendered "whales," includes also sharks, crocodiles, &c.; so that from the countless shoals of small fish to the great sea monsters, from the tiny insect to the king of birds, the waters and the air were suddenly made to swarm with creatures formed to live and sport in their respective elements.
gen 1:24SIXTH DAY. A farther advance was made by the creation of terrestrial animals, all the various species of which are included in three classes: (1) cattle, the herbivorous kind capable of labor or domestication. (Gen 1:24-31)
beasts of the earth--(2) wild animals, whose ravenous natures were then kept in check, and (3) all the various forms of
creeping things--from the huge reptiles to the insignificant caterpillars.
gen 1:26The last stage in the progress of creation being now reached--God said, Let us make man--words which show the peculiar importance of the work to be done, the formation of a creature, who was to be God's representative, clothed with authority and rule as visible head and monarch of the world.
In our image, after our likeness--This was a peculiar distinction, the value attached to which appears in the words being twice mentioned. And in what did this image of God consist? Not in the erect form or features of man, not in his intellect, for the devil and his angels are, in this respect, far superior; not in his immortality, for he has not, like God, a past as well as a future eternity of being; but in the moral dispositions of his soul, commonly called original righteousness (Ecc 7:29). As the new creation is only a restoration of this image, the history of the one throws light on the other; and we are informed that it is renewed after the image of God in knowledge, righteousness, and true holiness (Col 3:10; Eph 4:24).
gen 1:28Be fruitful, &c.--The human race in every country and age has been the offspring of the first pair. Amid all the varieties found among men, some black, some copper-colored, others white, the researches of modern science lead to a conclusion, fully accordant with the sacred history, that they are all of one species and of one family (Act 17:26). What power in the word of God! "He spake and it was done. He commanded and all things stood fast" [Psa 33:9]. "Great and manifold are thy works, Lord God Almighty! in wisdom hast thou made them all" [Psa 104:24]. We admire that wisdom, not only in the regular progress of creation, but in its perfect adaptation to the end. God is represented as pausing at every stage to look at His work. No wonder He contemplated it with complacency. Every object was in its right place, every vegetable process going on in season, every animal in its structure and instincts suited to its mode of life and its use in the economy of the world. He saw everything that He had made answering the plan which His eternal wisdom had conceived; and, "Behold it was very good" [Gen 1:31].