Charles H. Spurgeon on Psalms 104:19

The appointed rule of the great lights is now the theme for praise. The moon is mentioned first, because in the Jewish day the night leads the way. He appointed the moon for seasons. By the waxing and waning of the moon the year is divided into months, and weeks, and by this means the exact dates of the holy days were arranged. Thus the lamp of night is made to be of service to man, and in fixing the period of religious assemblies (as it did among the Jews) it enters into connection with his noblest being. Never let us regard the moon's motions as the inevitable result of inanimate impersonal law, but as the appointment of our God. The sun knoweth his going down. In finely poetic imagery the sun is represented as knowing when to retire from sight, and sink below the horizon. He never loiters on his way, or pauses as if undecided when to descend; his appointed hour for going down, although it is constantly varying, he always keeps to a second. We need to be aroused in the morning, but he arises punctually, and though some require to watch the clock to know the hour of rest, he, without a timepiece to consult, hides himself in the western sky the instant the set time has come. For all this man should praise the Lord of the sun and moon, who has made these great lights to be our chronometers, and thus keeps our world in order, and suffers no confusion to distract us.