The road and ascent to God, then, necessarily demands a habitual effort to renounce and mortify the appetites; the sooner this mortification is achieved, the sooner the soul reaches the top. But until the appetites are eliminated, a person will not arrive, no matter how much virtue he practices. For he will fail to acquire perfect virtue, which lies in keeping the soul empty, naked, and purified of every appetite.
– St. John of the Cross