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Genesis 1: 14-18
14 Then God said, Let there be lights in the firmament of the heavens to divide the day from the night; and serve as signals for the seasons, for days and years,
15 and let them be for lights in the expanse of the heavens to give light on the earth. And it was like that.
16 And God made the two great lights; the greater luminary to rule the day, and the lesser luminary to rule the night; He also made the stars.
17 And God set them in the firmament of the heaven to give light on the earth,
18 And to rule in the day and in the night, and to separate the light from the darkness. And God saw that it was good.
God himself at the beginning of creation saw that the creation of light on earth was necessary, and I create the sun, the star that lights us during the day and helps us to differentiate the day from the night or what is the same light of darkness.
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Note: @sirknight started a contest and its daily theme's are:
Sunday-Light
Monday-Darkness
Tuesday-AnimalKingdom
Wednesday-Structures
Thursday-ForcesinNature
Friday-LoveBeautyFreedom
Saturday-Agriculture