I answer that, Those corruptions especially are said to be infectious, which are of such a nature as to be transmitted from one subject to another:  hence contagious diseases, such as leprosy and murrain and the like, are said to be infectious.  Now the corruption of original sin is transmitted by the act of generation, as stated above (Q. 81, A. 1).  Therefore the powers which concur in this act, are chiefly said to be infected.  Now this act serves the generative power, in as much as it is directed to generation; and it includes delectation of the touch, which is the most powerful object of the concupiscible faculty.  Consequently, while all the parts of the soul are said to be corrupted by original sin, these three are said specially to be corrupted and infected.

Reply Obj. 1:  Original sin, in so far as it inclines to actual sins, belongs chiefly to the will, as stated above (A. 3).  But in so far as it is transmitted to the offspring, it belongs to the aforesaid powers proximately, and to the will, remotely.

Reply Obj. 2:  The infection of actual sin belongs only to the powers which are moved by the will of the sinner.  But the infection of original sin is not derived from the will of the contractor, but through his natural origin, which is effected by the generative power.  Hence it is this power that is infected by original sin.

Reply Obj. 3:  Sight is not related to the act of generation except in respect of remote disposition, in so far as the concupiscible species is seen through the sight.  But the delectation is completed in the touch.  Wherefore the aforesaid infection is ascribed to the touch rather than to the sight. ________________________

QUESTION 84

OF THE CAUSE OF SIN, IN RESPECT OF ONE SIN BEING THE CAUSE OF ANOTHER (In Four Articles)

We must now consider the cause of sin, in so far as one sin can be the cause of another.  Under this head there are four points of inquiry: 

(1) Whether covetousness is the root of all sins?

(2) Whether pride is the beginning of every sin?

(3) Whether other special sins should be called capital vices, besides pride and covetousness?

(4) How many capital vices there are, and which are they?
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FIRST ARTICLE [I-II, Q. 84, Art. 1]

Whether Covetousness Is the Root of All Sins?

Objection 1:  It would seem that covetousness is not the root of all sins.  For covetousness, which is immoderate desire for riches, is opposed to the virtue of liberality.  But liberality is not the root of all virtues.  Therefore covetousness is not the root of all sins.

Obj. 2:  Further, the desire for the means proceeds from desire for the end.  Now riches, the desire for which is called covetousness, are not desired except as being useful for some end, as stated in Ethic. i, 5.  Therefore covetousness is not the root of all sins, but proceeds from some deeper root.