Nicene and Post-Nicene Fathers, Vol. III:
Doctrinal Treatises of St. Augustin: Chapter 42

Chapter 42.—The Sacrament of Baptism Indicates Our Death with Christ to Sin, and Our Resurrection with Him to Newness of Life.

And this is the meaning of the great sacrament of baptism which is solemnized among us, that all who attain to this grace should die to sin, as He is said to have died to sin, because He died in the flesh, which is the likeness of sin; and rising from the font regenerate, as He arose alive from the grave, should begin a new life in the Spirit, whatever may be the age of the body?