John Calvin Commentary Genesis 17:12

"And he that is eight days old shall be circumcised among you, every male throughout your generations, he that is born in the house, or bought with money of any foreigner that is not of thy seed." — Genesis 17:12 (ASV)

And he that is eight days old shall be circumcised. God now prescribes the eighth day for circumcision, from which it appears that this was a part of that discipline under which He intended to keep His ancient people; for greater liberty is permitted today in the administration of baptism.

Some, however, maintain that we must not contend earnestly about the number of days, because the Lord spared the children on account of their tenderness, since it was not without danger to inflict a wound upon those who were newly born. For although He might have provided that circumcision should produce no harm or injury, yet there would be no absurdity in saying that He showed consideration for their tender age, in order to prove to the Jews His paternal love towards their children.

To others, this seems too superficial; therefore, they seek a spiritual mystery in the number of days. They think that the present life is allegorically signified by the seven days, and that God commanded infants to be circumcised on the eighth day to show that, although we must give attention to the mortification of the flesh throughout our entire life, it will not be completed until the end.

Augustine also thinks that it had reference to the resurrection of Christ, by which external circumcision was abolished and the truth of the figure was revealed. It is probable and consistent with reason that the number seven designated the course of the present life. Therefore, the eighth day might seem to have been chosen by the Lord to prefigure the beginning of a new life.

But because such a reason is never given in Scripture, I dare not affirm anything. Therefore, let it be enough to maintain what is certain and solid: namely, that God, in this symbol, has so represented the destruction of the old man, as also to show that He restores men to life.

He that is born in the house, or bought with money. When God commands Abraham to circumcise all who were under his authority, His special love towards holy Abraham is evident in this: that He embraces his whole family in His grace. We know that in the past, slaves were scarcely reckoned among the number of men.

But God, out of regard for His servant Abraham, adopts them as His own sons; nothing whatever can be added to this mercy. The pride of the flesh is also cast down, because God, without partiality, gathers together both freemen and slaves. But in the person of Abraham, He has prescribed it as a law to all His servants that they should endeavor to bring all who are subject to them into the same community of faith with themselves.

For every family of the pious ought to be a church. Therefore, if we desire to prove our piety, we must labor so that each one of us may have his household ordered in obedience to God. And Abraham is not only commanded to dedicate and offer to God those born in his house, but also whomever he might afterwards obtain.