_materially_ as they are in themselves. (See what is said of
ignorance, c. iii., s. i., nn. 3-5, p. 27.) This explains the
difference between _formal_ and _material_ sin. A _material_ sin would
be _formal_ also, did the agent know what he was doing. No sin is
culpable that is not _formal_. But, as has been said, there may be a
culpable perversion of the intellect, so that the man is the author of
his own obliquity or defect of vision. When Saul persecuted the
Christians, he probably sinned materially, not formally. When Caiphas
spoke the truth without knowing it, he said well materially, but ill
formally.

8. In looking at the means taken and the circumstances that accompany
those means, it is important to have a ready rule for pronouncing what
particular belongs to the means and what to the circumstances. Thus
Clytemnestra deals her husband Agamemnon a deadly stroke with an axe,
partly for revenge, partly that she may take to herself another
consort; is the deadliness of the blow part of the means taken or only
an accompanying circumstance? It is part of the means taken. The means
taken include every particular that is willed and chosen as making for
the end in view. The fatal character of the blow does make to that
end; if Agamemnon does not die, the revenge will not be complete, and
life with Aegisthus will be impossible. On the other hand, the fact
that Clytemnestra is the wife of the man whom she murders, is not a
point that her will rests upon as furthering her purpose at all; it is
an accompanying circumstance. This method of distinguishing means from
circumstance is of great value in casuistry.

9. It is clear that not every attendant circumstance affects the
morality of the means taken. Thus the blow under which Agamemnon sank
was neither more nor less guiltily struck because it was dealt with an