"...before setting to work for God and to fight against the devil, first calculate your forces; and if you consider yourself well enough equipped to begin, you are a fool, because the tower to be built costs an outrageous price, and the enemy coming out to meet you is an angel, before whom you are of no account. Get to know yourself so well that you cannot contemplate yourself without flinching. Then there will be room for hope. In the sure knowledge that you are obliged to do the impossible in Him who strengthens you, then you are ready for a task which can be performed only through the Cross."
--Jacques Maritain, as quoted by Father Gerald Vann, O.P. in The Seven Swords
