John Calvin Commentary Genesis 1:5

"And God called the light Day, and the darkness he called Night. And there was evening and there was morning, one day." — Genesis 1:5 (ASV)

And God called the light. That is, God willed that there should be a regular alternation of days and nights, which also followed immediately when the first day ended. For God removed the light from view, so that night might be the beginning of another day. However, what Moses says admits a double interpretation: either that this was the evening and morning belonging to the first day, or that the first day consisted of the evening and the morning.

Whichever interpretation is chosen, it makes no difference to the meaning, for he simply understands the day to have been made up of two parts. Furthermore, he begins the day with the evening, according to the custom of his nation. It is pointless to dispute whether this is the best and legitimate order or not. We know that darkness preceded time itself; when God withdrew the light, he closed the day. I do not doubt that the most ancient fathers, for whom the coming night was the end of one day and the beginning of another, followed this mode of reckoning. Although Moses did not intend here to prescribe a rule that it would be criminal to violate, yet (as we have now said) he adapted his discourse to the received custom. Therefore, just as the Jews foolishly condemn all the reckonings of other people, as if God had sanctioned this one alone, so again are those equally foolish who contend that this modest reckoning, which Moses approves, is absurd.

The first day. Here the error of those who maintain that the world was made in a moment is clearly refuted. For it is too extreme a quibble to contend that Moses distributes the work, which God perfected at once, into six days merely for the purpose of conveying instruction.

Let us rather conclude that God himself took the space of six days to adapt his works to human capacity. We carelessly pass over the infinite glory of God, which shines forth here. From where does this arise, if not from our excessive dullness in considering his greatness?

Meanwhile, the vanity of our minds carries us away to other things. To correct this fault, God applied the most suitable remedy when he distributed the creation of the world into successive portions, so that he might fix our attention and compel us—as if he had laid his hand upon us—to pause and reflect.

For the confirmation of the interpretation mentioned above, a passage from Ecclesiasticus is incorrectly cited: He who lives forever created all things at once . For the Greek adverb κοινῇ, which the writer uses, means nothing of the sort; nor does it refer to time, but to all things universally.