3. How Original Sin is Contracted

67. As to the third article and the third question [nn.49, 17].

In line with this way [n.48] it is said that the soul contracts original sin by the intermediary of the flesh - not in such a way that the flesh as it were causes the sin by some quality quasi-caused [n.29] in the soul, but by the fact that the flesh is sown with concupiscence, and from this the organic body is formed and the soul infused into it [n.63], constituting a person who is a son of Adam. This person, then, because he is a natural son of Adam, is in debt for original justice (given by God to Adam for all his sons) and lacks it; therefore he has original sin. So the sin is contracted in the flesh insofar as the flesh is a natural reason, and from this reason the person is proved to owe the justice that through Adam’s sin he lacks.