The Lord looks at his work on the first day. The work is good in God’s eyes. And when it is good in God's eyes, it is really good and beautiful. The light is good—good for the purpose with which the Lord created it. In creation, light is the first requirement for life on earth.
Through his creation of the light God has made a separation between light and dark, between day and night. We read the term to separate
five times in Genesis 1:1–31. The other instances are in Genesis 1:6–7, Genesis 1:14 and Genesis 1:18. During the six days that the Lord makes the earth habitable, he makes separations to order everything in the right way.
4 And God saw that the light was good. And God separated the light from the darkness.