56 Q. How many things are necessary to make a sin mortal?
A. To make a sin mortal three things are necessary: a grievous matter,
sufficient reflection, and full consent of the will.
“Grievous matter.” To steal is a sin. Now, if you steal only a pin the
act of stealing in that case could not be a mortal sin, because the
“matter,” namely, the stealing of an ordinary pin, is not grievous. But
suppose it was a diamond pin of great value, then it would surely be
“grievous matter.” “Sufficient reflection,” that is, you must know what
you are doing at the time you do it. For example, suppose while you
stole the diamond pin you thought you were stealing a pin with a small
piece of glass, of little value, you would not have sufficient
reflection and would not commit a mortal sin till you found out that
what you had stolen was a valuable diamond; if you continued to keep it
after learning your mistake, you would surely commit a mortal sin. “Full
consent.” Suppose you were shooting at a target and accidentally killed
a man: you would not have the sin of murder, because you did not will or
wish to kill a man.
Therefore three things are necessary that your act may be a mortal sin:
(1) The act you do must be bad, and sufficiently important; (2) You must
reflect that you are doing it, and know that it is wrong; (3) You must
do it freely, deliberately, and willfully.
