We proceed to the second article thus:

1. It seems that there are many original sins in one man. For it is said in Ps.51:5: "Behold, I was shapen in iniquity; and in sin [28] did my mother conceive me." The sin in which one is conceived is original sin. There are therefore several original sins in one man.

2. Again, one and the same habit does not cause us to tend towards opposite things. For a habit inclines us through a modification of nature, which tends in one direction. But original sin, even in one man, inclines him to different and opposite sins. It is therefore not one habit, but several.

3. Again, original sin infects all parts of the soul. But the several parts of the soul are separate subjects of sin, as was explained in Q.74, and the same sin cannot be in separate subjects. It seems, then, that original sin is not one, but many.

On the other hand: it is said in John 1:29: "Behold the Lamb of God, which taketh away the sin of the world." As the gloss explains, the singular is used because "the sin of the world," which is original sin, is one.

I answer: there is only one original sin in any one man. We may see the reason for this in two ways. We may see it from the cause of original sin. It is only the first sin of our first parent that is transmitted to posterity, as we said in Q.81, Art.2. The original sin that is in any one man is therefore numerically one, while it is also proportionately one in all men, that is, one in respect of its first beginning. We may see the reason also if we consider the essence of original sin itself. Any disordered disposition is considered to be one if its cause is of one kind, and to be numerically one if it occurs in a single subject. This is obvious in the case of bodily sickness. There may indeed be many kinds of sickness arising from different causes, such as excessive heat or cold, or lesion of the lungs or of the liver. But a sickness of any one kind in one man is numerically one. Now there is only one cause of the corrupt disposition which we call original sin. Its cause is the privation of original justice, which took away from man the subjection of his mind to God. Original sin is therefore of one kind, and can only be numerically one in any one man. It is, however, numerically different in different men, though one in kind and in proportion.

On the first point: the plural "in sins" is here used in the customary manner of divine Scripture, which frequently uses the plural instead of the singular, as for example in Matt.2:20: "they are dead which sought the young child's life." It is used either because all natural sins virtually pre-exist in original sin as their principle, so that original sin is virtually many; or because the sin transmitted to us through generation from our first parent includes many deformities, such as pride, disobedience, gluttony, and the like; or because many parts of the soul are infected by original sin.

On the second point: the same habit cannot incline us to opposite things directly and of itself, by means of its own form. But it can do so indirectly and accidentally, by taking away a preventative. The elements of a composite body tend in different directions when its harmony is destroyed. The several powers of the soul also tend in different directions when the harmony of original justice is taken away.

On the third point: original sin infects the different powers of the soul as parts of a single whole, just as original justice once held all parts of the soul together as a single whole. There is therefore only one original sin, just as there is only one fever in one man, though different parts of his body may be aggravated by it.

[28] Migne: in peccatis (plural).