Such is the power of this sacrament: it is a sacrament of new life which begins here and now with the forgiveness of all past sins, and will be brought to completion in the resurrection of the dead. You have been buried with Christ by baptism into death in order that, as Christ has risen from the dead, you also may walk in newness of life.
You are walking now by faith, still on pilgrimage in a mortal body away from the Lord; but he to whom your steps are directed is himself the sure and certain way for you: Jesus Christ, who for our sake became man. For all who fear him he has stored up abundant happiness, which he will reveal to those who hope in him, bringing it to completion when we have attained the reality which even now we possess in hope.
This is the octave day of your new birth. Today is fulfilled in you the sign of faith that was prefigured in the Old Testament by the circumcision of the flesh on the eighth day after birth. When the Lord rose from the dead, he put off the mortality of the flesh; his risen body was still the same body, but it was no longer subject to death. By his resurrection he consecrated Sunday, or the Lord’s day. Though the third after his passion, this day is the eighth after the Sabbath, and thus also the first day of the week.
And so your own hope of resurrection, though not yet realized, is sure and certain, because you have received the sacrament or sign of this reality, and have been given the pledge of the Spirit. If, then, you have risen with Christ, seek the things that are above, where Christ is seated at the right hand of God. Set your hearts on heavenly things, not the things that are on earth. For you have died and your life is hidden with Christ in God. When Christ, your life, appears, then you too will appear with him in glory.
*From Office of Readings, sermon by Saint Augustine, bishop (Sermo 8 in octava Paschae 1, 4: PL 46, 838. 841)