Psalms 104:19

He appointed the moon for seasons - Genesis 1:14. That is, The moon, as well as the sun, is appointed to divide time; to determine its progress; to indicate the return of festival occasions, or appointed times to be observed in any manner. It is, in fact, the foundation of the division of the year into “months,” and consequently the indication of all that is to be observed in the “months” of the year. But for this, there would be no natural divisions of time except those of day and night, and of the year. How great an advantage it is for the purpose of life, to have time broken up into brief intervals or periods which can be marked and remembered, both in our private life and in history, it is not necessary to say. God has been pleased to add to the natural divisions of time into days, and years, and months, an “artificial” division - the “fourth” part of the moon’s course - “a week,” indicated by the Sabbath, thus greatly facilitating the plans of life in regard to stated times or “seasons,” and especially in regard to religious observances. The idea in the passage before us is, that the whole arrangement is one of benevolence, promoting the comfort of man, and bringing the ideas of succession, variety, and beauty into the system.

The sun knoweth his going down - As if conscious of what he is doing, he knows the exact time of setting, and never varies, but always obeys the divine command; never sets “before” his time - unexpectedly shortening the day, and leaving man in sudden darkness in the midst of his toil; and never lingers above the horizon “after” the moment has come for his setting, but withdraws at the exact time, enabling man to close his toil, and seek repose, and giving an opportunity for another class of creatures to come forth on the animated scene. Their good is regarded as well as that of man; and the operations of nature are so arranged as to promote the welfare of all.