Augustine of Hippo, On Marriage and Concupiscence II.47: The Scriptures Repeatedly Teach Us that All Sin in One

Still let him ply his question: “By what means may sin be discovered in an infant?” He may find an answer in the inspired pages: “By one man sin entered into the world, and death by sin; and so death passed upon all men, for in him all sinned.” “Through the offence of one many are dead.” “The judgment was from one to condemnation.” “By one man’s offence death reigned by one.” “By the offence of one, Judgment came upon all men to condemnation.” “By one man’s disobedience many were made sinners.” Behold, then, “by what means sins may be discovered in an infant.” Let him now believe in original sin; let him permit infants to come to Christ, that they may be saved. [XXVIII.] What means this passage of his: “He sins not who is born; he sins not who begat him; He sins not who created him. Amidst these intrenchments of innocence, therefore, what are the breaches through which you pretend that sin entered?” Why does he search for a hidden chink when he has an open door? “By one man,” says the apostle; “through the offence of one,” says the apostle; “By one man’s disobedience,” says the apostle. What does he want more? What does he require plainer? What does he expect to be more impressively repeated?