4 For, with respect to what you say, that the aspect of an infant in the first days after its birth is not pure, so that any one of us would still shudder at kissing it, we do not think that this ought to be alleged as any impediment to heavenly grace. For it is written, “To the pure all things are pure.” Nor ought any of us to shudder at that which God has condescended to make. For although the infant is still fresh from its birth, yet it is not such that any one should shudder at kissing it in giving grace and in making peace; since in the kiss of an infant every one of us ought for his very religion's sake, to consider the still recent hands of God themselves, which in some sort we are kissing, in the man lately formed and freshly born, when we are embracing that which God has made.
For in respect of the observance of the eighth day in the Jewish circumcision of the flesh, a sacrament was given beforehand in shadow and in usage; but when Christ came, it was fulfilled in truth. For because the eighth day, that is, the first day after the Sabbath, was to be that on which the Lord should rise again, and should quicken us, and give us circumcision of the spirit, the eighth day, that is, the first day after the Sabbath, and the Lord's day, went before in the figure; which figure ceased when by and by the truth came, and spiritual circumcision was given to us.
Source: The Epistles of Cyprian (New Advent)