According to the Catholic Faith we are bound to hold that the first
sin of the first man is transmitted to his descendants, by way of
origin. For this reason children are taken to be baptized soon after
their birth, to show that they have to be washed from some
uncleanness. The contrary is part of the Pelagian heresy, as is clear
from Augustine in many of his books [*For instance, Retract. i, 9; De
Pecc. Merit. et Remiss. ix; Contra Julian. iii, 1; De Dono Persev. xi,
xii.]
In endeavoring to explain how the sin of our first parent could be
transmitted by way of origin to his descendants, various writers have
gone about it in various ways. For some, considering that the subject
of sin is the rational soul, maintained that the rational soul is
transmitted with the semen, so that thus an infected soul would seem
to produce other infected souls. Others, rejecting this as erroneous,
endeavored to show how the guilt of the parent's soul can be
transmitted to the children, even though the soul be not transmitted,
from the fact that defects of the body are transmitted from parent to
child—thus a leper may beget a leper, or a gouty man may be the father
of a gouty son, on account of some seminal corruption, although this
corruption is not leprosy or gout. Now since the body is proportionate
to the soul, and since the soul's defects redound into the body, and
vice versa, in like manner, say they, a culpable defect of the soul is
passed on to the child, through the transmission of the semen, albeit
the semen itself is not the subject of the guilt.
But all these explanations are insufficient. Because, granted that
some bodily defects are transmitted by way of origin from parent to
child, and granted that even some defects of the soul are transmitted
in consequence, on account of a defect in the bodily habit, as in the
case of idiots begetting idiots; nevertheless the fact of having a
defect by the way of origin seems to exclude the notion of guilt,
which is essentially something voluntary. Wherefore granted that the
rational soul were transmitted, from the very fact that the stain on
the child's soul is not in its will, it would cease to be a guilty
stain binding its subject to punishment; for, as the Philosopher says
(Ethic. iii, 5), "no one reproaches a man born blind; one rather takes
pity on him."
Therefore we must explain the matter otherwise by saying that all men
born of Adam may be considered as one man, inasmuch as they have one
common nature, which they receive from their first parents; even as in
civil matters, all who are members of one community are reputed as one
body, and the whole community as one man. Indeed Porphyry says
(Praedic., De Specie) that "by sharing the same species, many men are
one man." Accordingly the multitude of men born of Adam, are as so
many members of one body. Now the action of one member of the body, of
the hand for instance, is voluntary not by the will of that hand, but
by the will of the soul, the first mover of the members. Wherefore a
murder which the hand commits would not be imputed as a sin to the
hand, considered by itself as apart from the body, but is imputed to
it as something belonging to man and moved by man's first moving
principle. In this way, then, the disorder which is in this man born
of Adam, is voluntary, not by his will, but by the will of his first
parent, who, by the movement of generation, moves all who originate
from him, even as the soul's will moves all the members to their
actions. Hence the sin which is thus transmitted by the first parent
to his descendants is called "original," just as the sin which flows
from the soul into the bodily members is called "actual." And just as
the actual sin that is committed by a member of the body, is not the
sin of that member, except inasmuch as that member is a part of the
man, for which reason it is called a "human sin"; so original sin is
not the sin of this person, except inasmuch as this person receives
his nature from his first parent, for which reason it is called the
"sin of nature," according to Eph. 2:3: "We . . . were by nature
children of wrath."