Passage
and to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
and to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
Genesis 1:16 And God made the two great lights; the greater light to rule the day, and the lesser light to rule the night: [he made] the stars also.
Genesis 1:17 And God set them in the firmament of heaven to give light upon the earth,
Genesis 1:18 and to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
Genesis 1:19 And there was evening and there was morning, a fourth day.
Genesis 1:20 And God said, Let the waters swarm with swarms of living creatures, and let birds fly above the earth in the open firmament of heaven.
The verse centers on "light", "darkness", "rule", "over", "night", "divide", and "good". It is saying that the contrast between light and darkness marks a real divide in how people respond to God's work.
The nearby context moves from verse 17's "And God set them in the firmament..." into verse 19's "And there was evening and there was...", so "light" and "darkness" belong inside that flow. In Genesis context, the local focus is creation, human rebellion, covenant promise, and God's providence.
A plain takeaway is to answer the verse's own emphasis on "light" and "darkness" with trust shaped by these words, not by a vague optimism outside the passage.