The first obvious and natural division of the whole day-interval is into the light part and the dark part. As we have seen in Genesis, the evening and the morning are the day. Since Palestine is a sub-tropical country, these would never differ very greatly in length, even at midsummer or midwinter.
The next subdivision, of the light part of the day, is into morning, noon and evening. As David says in the fifty-fifth Psalm—
"Evening, and morning, and at noon, will I pray."
None of these three subdivisions were marked out definitely in their beginning or their ending, but each contained a definite epoch. Morning contained the moment at which the sun rose; noon the moment at which he was at his greatest height, and was at the same time due south; evening contained the moment at which the sun set.
In the early Scriptures of the Old Testament, the further divisions of the morning and the evening are still natural ones.
For the progress of the morning we have, first, the twilight, as in Job—
"Let the stars of the twilight thereof be dark;
Let it look for light but have none;
Neither let it see the eyelids of the morning."
Then, daybreak, as in the Song of Solomon—
"Until the day break (literally, breathe) and the shadows flee away,"
where the reference is to the cool breezes of twilight. So too in Genesis, in Joshua, in the Judges and in Samuel, we find references to the "break of day" (literally, the rising of the morning, or when it became light to them) and "the dawning of the day" or "about the spring of the day."