On the contrary, Gregory (Moral. xxxi, 17) enumerates certain special vices under the name of capital.

I answer that, The word capital is derived from caput (a head).  Now the head, properly speaking, is that part of an animal’s body, which is the principle and director of the whole animal.  Hence, metaphorically speaking, every principle is called a head, and even men who direct and govern others are called heads.  Accordingly a capital vice is so called, in the first place, from “head” taken in the proper sense, and thus the name “capital” is given to a sin for which capital punishment is inflicted.  It is not in this sense that we are now speaking of capital sins, but in another sense, in which the term “capital” is derived from head, taken metaphorically for a principle or director of others.  In this way a capital vice is one from which other vices arise, chiefly by being their final cause, which origin is formal, as stated above (Q. 72, A. 6).  Wherefore a capital vice is not only the principle of others, but is also their director and, in a way, their leader:  because the art or habit, to which the end belongs, is always the principle and the commander in matters concerning the means.  Hence Gregory (Moral. xxxi, 17) compares these capital vices to the “leaders of an army.”

Reply Obj. 1:  The term “capital” is taken from caput and applied to something connected with, or partaking of the head, as having some property thereof, but not as being the head taken literally.  And therefore the capital vices are not only those which have the character of primary origin, as covetousness which is called the “root,” and pride which is called the beginning, but also those which have the character of proximate origin in respect of several sins.

Reply Obj. 2:  Sin lacks order in so far as it turns away from God, for in this respect it is an evil, and evil, according to Augustine (De Natura Boni iv), is “the privation of mode, species and order.”  But in so far as sin implies a turning to something, it regards some good:  wherefore, in this respect, there can be order in sin.

Reply Obj. 3:  This objection considers capital sin as so called from the punishment it deserves, in which sense we are not taking it here. ________________________

FOURTH ARTICLE [I-II, Q. 84, Art. 4]

Whether the Seven Capital Vices Are Suitably Reckoned?

Objection 1:  It would seem that we ought not to reckon seven capital vices, viz. vainglory, envy, anger, sloth, covetousness, gluttony, lust.  For sins are opposed to virtues.  But there are four principal virtues, as stated above (Q. 61, A. 2).  Therefore there are only four principal or capital vices.

Obj. 2:  Further, the passions of the soul are causes of sin, as stated above (Q. 77).  But there are four principal passions of the soul; two of which, viz. hope and fear, are not mentioned among the above sins, whereas certain vices are mentioned to which pleasure and sadness belong, since pleasure belongs to gluttony and lust, and sadness to sloth and envy.  Therefore the principal sins are unfittingly enumerated.