As delusions obscure and pervert the operations of the mind, so the passions hamper the will, and at times hold it captive. As a result of original sin man's will is not only weakened, but his nature inclines inordinately to one of the eleven passions. This inclination is called his predominant passion. It is inborn in him and permeates his entire temperament. The predominant passion has so great an influence on his daily life, when not directed by a good will, that the saints called it man's greatest enemy.
Love is the root of all the passions. It is the great motive power of life. Even fear and desire spring from it. Owing to his selfish nature some form of self-love is always the foundation of man's predominant passion. He should guard against it especially because the predominant passion invariably tends to one of the seven capital sins, and so may easily pave the way for vices that will hurry him to temporal excess and eternal ruin.