Chapter 16 — Part II: The Sacraments — Baptism
Section 93. Concupiscence Which Remains After Baptism Is No Sin — We must confess, however, that concupiscence, or the fuel of sin, still remains, as the Council declares in the same place. But concupiscence does not constitute sin, for, as St. Augustine observes, in children who have been baptised the guilt of concupiscence is removed, (the concupiscence itself) remains for probation; and in another place he says: the guilt of concupiscence is pardoned in Baptism, but its infirmity remains. For concupiscence which is the effect of sin is nothing more than an appetite of the soul in itself repugnant to reason. But if it is not accompanied by the consent of the will or by negligence, it is very far from being sin.