Genesis 1:14

Verse Genesis 1:14. And God said, Let there be lights, c.] One principal office of these was to divide between day and night. When night is considered a state of comparative darkness, how can lights divide or distinguish it? The answer is easy: The sun is the monarch of the day, which is the state of light the moon, of the night, the state of darkness. The rays of the sun, falling on the atmosphere, are refracted and diffused over the whole of that hemisphere of the earth immediately under his orb; while those rays of that vast luminary which, because of the earth's smallness in comparison of the sun, are diffused on all sides beyond the earth, falling on the opaque disc of the moon, are reflected back upon what may be called the lower hemisphere, or that part of the earth which is opposite to the part which is illuminated by the sun: and as the earth completes a revolution on its own axis in about twenty-four hours, consequently each hemisphere has alternate day and night. But as the solar light reflected from the face of the moon is computed to be 50,000 times less in intensity and effect than the light of the sun as it comes directly from himself to our earth, (for light decreases in its intensity as the distance it travels from the sun increases,) therefore a sufficient distinction is made between day and night, or light and darkness, notwithstanding each is ruled and determined by one of these two great lights; the moon ruling the night, i.e., reflecting from her own surface back on the earth the rays of light which she receives from the sun. Thus both hemispheres are to a certain degree illuminated: the one, on which the sun shines, completely so; this is day: the other, on which the sun's light is reflected by the moon, partially; this is night. It is true that both the planets and fixed stars afford a considerable portion of light during the night, yet they cannot be said to rule or to predominate by their light, because their rays are quite lost in the superior splendour of the moon's light.

And let them be for signs] לאתת leothoth. Let them ever be considered as continual tokens of God's tender care for man, and as standing proofs of his continual miraculous interference; for so the word את oth is often used. And is it not the almighty energy of God that upholds them in being? The sun and moon also serve as signs of the different changes which take place in the atmosphere, and which are so essential for all purposes of agriculture, commerce, c.

For seasons] מועדים moadim For the determination of the times on which the sacred festivals should be held. In this sense the word frequently occurs; and it was right that at the very opening of his revelation God should inform man that there were certain festivals which should be annually celebrated to his glory. Some think we should understand the original word as signifying months, for which purpose we know the moon essentially serves through all the revolutions of time.

For days] Both the hours of the day and night, as well as the different lengths of the days and nights, are distinguished by the longer and shorter spaces of time the sun is above or below the horizon.

And years.] That is, those grand divisions of time by which all succession in the vast lapse of duration is distinguished. This refers principally to a complete revolution of the earth round the sun, which is accomplished in 365 days, 5 hours, 48 minutes, and 48 seconds; for though the revolution is that of the earth, yet it cannot be determined but by the heavenly bodies.