Genesis 1:8

Firmament - Expanse or vault over the earth; sky.

Then called God to the expanse, heaven. - This expanse is, then, the proper and original skies. We have here an interesting and instructive example of the way in which words expand in their significance from the near, the simple, the obvious, to the far and wide, the complex and the inferential: The heaven, in the first instance, meant the open space above the surface in which we breathe and move, in which the birds fly and the clouds float. This is the atmosphere. Then it stretches away into the seemingly boundless regions of space, in which the countless orbs of luminous and of opaque surfaces circumambulate. Then the heavens come to signify the contents of this indefinitely augmented expanse, - the celestial luminaries themselves. Then, by a still further enlargement of its meaning, we rise to the heaven of heavens, the inexpressibly grand and august presence-chamber of the Most High, where the cherubim and seraphim, the innumerable company of angels, the myriads of saints, move in their several grades and spheres, keeping the charge of their Maker, and realizing the joy of their being. This is the third heaven 2 Corinthians 12:2 to the conception of which the imaginative capacity of the human mind rises by an easy gradation. Having once attained to this majestic conception, man is so far prepared to conceive and compose that sublime sentence with which the book of God opens, - "In the beginning God created 'the heavens' and the earth."

The expanse, or aerial space, in which this arrangement of things has been effected, having received its appropriate name, is recognized as an accomplished fact, and the second day is closed.

1:6-8 We have here an account of the second day's work, the creation of the firmament. In which observe, 1. The command of God; Let there be a firmament - An expansion; so the Hebrew word signifies, like a sheet spread, or a curtain drawn out. This includes all that is visible above the earth, between it and the third heavens, the air, its higher, middle, and lower region, the celestial globe, and all the orbs of light above; it reaches as high as the place where the stars are fixed, for that is called here the firmament of heaven, Genesis 1:14,15, and as low as the place where the birds fly for that also is called the firmament of heaven, Genesis 1:20. 2. The creation of it: and God made the firmament. 3. The design of it; to divide the waters from the waters-That is, to distinguish between the waters that are wrapt up in the clouds, and those that cover the sea; the waters in the air, and those in the earth. 4. The naming it; He called the firmament Heaven - 'Tis the visible heaven, the pavement of the holy city. The height of the heavens should mind us of God's supremacy, and the infinite distance that is between us and him; the brightness of the heavens, and their purity, should mind us of his majesty, and perfect holiness; the vastness of the heavens, and their encompassing the earth, and influence upon it, should mind us of his immensity and universal providence.