Genesis 1:4 - Clarke's commentary and critical notes on the Bible

And God saw the light, that it was good: and God divided the light from the darkness. God divided the light from the darkness - This does not imply that light and darkness are two distinct substances, seeing darkness is only the privation of light; but the words simply refer us by anticipation to the rotation of the earth round its own axis once in twenty-three hours, fifty-six minutes, and four seconds, which is the cause of the distinction between day and night, by bringing the different parts of the surface of the earth successively into and from under the solar rays; and it was probably at this moment that God gave this rotation to the earth, to produce this merciful provision of day and night. For the manner in which light is supposed to be produced, see Genesis 1:16, under the word sun.