"If our hand strike a fellow-creature unjustly, though the hand has itself no will, yet it is considered guilty, not indeed as viewed separately by itself, but inasmuch as it is united to the rest of the body, and to the soul, forming one human being therewith, and thus sharing in the will of the soul with which it is connected.
"Also the sin committed inwardly by the human will, by a bad desire, belongs to the whole human being.
"Of the original sin in which we are born we are not personally guilty with our own personal will, but our nature is guilty of it by the will of Adam, our head, with whom we form one moral body through the human nature which we derive from him. * * * The Catholic Church teaches that Adam, by his sin, has not only caused harm to himself, but to the whole human race; that by it he lost the supernatural justice and holiness which he received gratuitously from God, and lost it, not only for himself, but also for all of us; and that he, having stained himself with the sin of disobedience, has transmitted not only death and other bodily pains and infirmities to the whole human race, but also sin, which is the death of the soul.
"The teaching of the Council of Trent (Session V) is confirmed by these words of St. Paul: 'Wherefore as by one man sin entered into this world, and by sin death; and so death passed upon all men, in whom all have sinned' (Rom. v:12).
"Surely the early Christians believed in original sin, as it can be gathered from what St. Augustine said to Pelagius, opposing him on the matter: 'I did not invent original sin, which Catholic faith holds from ancient time; but thou, who deniest it, thou, without doubt, art a new heretic" (De nuptiis, lib. xi, c. 12).
"It may be said that this belief is as old as the human race, for traces of this ancient tradition are spread in all nations, insomuch that Voltaire had to confess that 'The fall of man is the base of the theology of nearly all ancient people' (Philosophic de l'histoire, chapter xvii).
"Beside the guilt of original sin, which is that habitual state of sinfulness in which we are born (because our human nature is justly considered to have consented in Adam to the rejection of original justice), there is also in man the stain of original sin, entailing the privation in the human soul of that supernatural lustre which, had we born in the state of original justice, we all should have had.
"As neither Adam nor any of his offspring could repair the evil done by his sin, we should ever have remained in the state of original sin and degradation in which we were born, and we should have been forever shut out from the Beatific Vision of God in Heaven, had not God, in his infinite mercy, provided for us a Redeemer."
The Incarnation of God the Son: Respecting this great mystery, Catholics believe that the Holy Trinity, out of infinite mercy, decreed to provide for us a Redeemer, who could suffer, and suffer as an individual of the human race, and at the same time be in himself so exalted as to be able to give infinite value to his sufferings; because sin, being an offense against the infinite majesty of God could only be atoned for by an expiation of infinite value.
"To accomplish this end, God the Son, the second person of the Holy Trinity, the Eternal Word, chose the Blessed Virgin Mary of Nazareth, to become his Mother, and on receiving her consent, he, by the supernatural agency of the Holy Spirit, took human flesh from her, and thus became man, and his holy name is Jesus Christ.