Genesis 1:15

Firmament - Expanse or vault over the earth; sky.

Let - To hinder or obstruct.

To shine upon the earth. - The first day spreads the shaded gleam of light over the face of the deep. The fourth day unfolds to the eye the lamps of heaven, hanging in the expanse of the skies, and assigns to them the office of "shining upon the earth." A threefold function is thus attributed to the celestial orbs - to divide day from night, to define time and place, and to shine on the earth. The word of command is here very full, running over two verses, with the exception of the little clause, "and it was so," stating the result.

1:14-19 This is the history of the fourth day's work, the creating the sun, moon and stars. Of this we have an account, 1. In general, verse 14, 15. where we have, (1.) The command given concerning them.

Let there be lights in the firmament of heaven — God had said, Genesis 1:3 Let there be light, and there was light; but that was, as it were, a chaos of light, scattered and confused; now it was collected and made into several luminaries, and so rendered both more glorious and more serviceable. (2.) The use they were intended to be of to this earth. [1.] They must be for the distinction of times, of day and night, summer and winter. [2.] They must be for the direction of actions: they are for signs of the change of weather, that the husbandman may order his affairs with discretion. They do also give light upon the earth - That we may walk John 11:9 and work John 9:4 according as the duty of every day requires. The lights of heaven do not shine for themselves, nor for the world of spirits above, they need them not; but they shine for us, and for our pleasure and advantage. Lord, what is man that he should be thus regarded, Psalms 8:3,4. 2. In particular, Genesis 1:16,17,18, The lights of heaven are the sun, moon and stars, and these all are the work of God's hands. (1.) The sun is the greatest light of all, and the most glorious and useful of all the lamps of heaven; a noble instance of the Creator's wisdom, power and goodness, and an invaluable blessing to the creatures of this lower world. (2.) The moon is a lesser light, and yet is here reckoned one of the greater lights, because, though in regard of its magnitude, it is inferior to many of the stars, yet in respect of its usefulness to the earth, it is more excellent than they. (3.) He made the stars also - Which are here spoken of only in general; for the scriptures were written not to gratify our curiosity, but to lead us to God. Now, these lights are said to rule, Genesis 1:16,18; not that they have a supreme dominion as God has, but they are rulers under him. Here the lesser light, the moon, is said to rule the night; but Psalms 136:9 the stars are mentioned as sharers in that government, the moon and stars to rule by night. No more is meant, but that they give light, Jeremiah 31:35. The best and most honourable way of ruling is, by giving light, and doing good.