“And let them be for lights in the expanse of the heavens to give light on the earth’; and it was so.” (Genesis 1:15, NASB)
There does not seem to be much mention of this verse in commentaries etc. I would like to point out several things. Though these things are small we must remember that this is the record of God’s work in God’s word!
Notice how God assigns being and purpose to the light. Up to this verse God has set out four categories. First, God creates (v 3, 6/7, 11/12). Second, God organized (v 4, 9). Third, God called or named (v 5, 8, 10). Forth, in verse 14 and 15 God introduces purpose.
Verse 14 begins to set out the purpose of the lights, to serve as signs. They will be for signs of seasons, signs of days and signs of years. Verse 15 expands on this, the further purpose of the light is to light the earth. This is the beginning of several purposes that God uses to prepare the earth to receive life (v 22, 26, 28, 29, 30).