John Calvin Commentary Genesis 7:8

"Of clean beasts, and of beasts that are not clean, and of birds, and of everything that creepeth upon the ground," — Genesis 7:8 (ASV)

Of clean beasts. Moses now explains—what had previously been doubtful—how the animals were gathered together into the ark, and says that they came of their own accord. If this should seem absurd to anyone, let him recall what was said previously: that in the beginning every kind of animal presented itself to Adam, that he might give them names.

And truly, we dread the sight of wild beasts for no other reason than this: because we have shaken off the yoke of God, we have lost that authority over them with which Adam was endowed. Now, it was a kind of restoration of the former state of things when God brought to Noah those animals that he intended to be preserved through Noah’s labor and service.

For Noah retained the untamed animals in his ark in the very same way that hens and geese are preserved in a coop. And it is not added unnecessarily that the animals themselves came as God had instructed Noah, for it shows that the blessing of God rested on Noah’s obedience, so that his labor should not be in vain.

It was impossible, humanly speaking, that such an assemblage of all animals should take place in a moment. But because Noah, simply entrusting the event to God, carried out what was commanded of him, God, in return, gave power to his own command, so that it might not be without effect. Properly speaking, this was a promise of God attached to his commands.

Therefore, we must conclude that Noah’s faith was more effective than all snares and nets for capturing animals, and that lions, wolves, and tigers meekly entered by the very same gate into the ark with oxen and lambs.

This is the only way we can overcome all difficulties: while—being persuaded that what is impossible for us is easy for God—we derive eagerness from hope.

It has been stated previously that the animals entered by pairs. We have also mentioned the different opinions of interpreters regarding the month in which the deluge took place.

For since the Hebrews begin their year in sacred things from March, but in earthly affairs from September—or—which is the same thing—since the two equinoxes form with them a double beginning of the year, some think that the sacred year, and some the political, is intended here.

But because the former method of reckoning the years was divinely appointed and is also more consistent with nature, it seems probable that the deluge began around the time of spring.