Mortification Is the Habitual Weakening of Sin

Sometimes one sinful desire hits a man harder than another man, or harder than a different sinful desire does. This might be due to natural tendencies in him, frequent opportunities to be tempted, or simply because Satan has a grip on the man with which to manipulate him. When this happens, even though he still knows the truth, the sinful desire darkens his mind as with a mist, and his corrupt affections and passions are thus set free to wreak havoc.