Fr. Timothy Gallagher discusses the Twelve Rule:
"The enemy acts like a woman, in being weak against vigor and strong of will. Because, as it is the way of the woman when she is quarreling with some man to lose heart, taking flight when the man shows her much courage: and on the contrary, if the man, losing heart, begins to fly, the wrath, revenge, and ferocity of the woman is very great, and so without bounds; in the same manner, it is the way of the enemy to weaken and lose heart, his temptations taking flight, when the person who is exercising himself in spiritual things opposes a bold front against the temptations of the enemy, doing diametrically the opposite. And on the contrary, if the person who is exercising himself commences to have fear and lose heart in suffering the temptations, there is no beast so wild on the face of the earth as the enemy of human nature in following out his damnable intention with so great malice."