“Because when a person regards the height of goodness in his mind, he then builds a high wall of faith by virtue of the work of God. Then he ascends above that rational faith, which shows him God in the power of His Divinity, and on it he builds bulwarks of virtue higher than the wall. How? He finds that it is not enough to have faith in God, and so builds virtues that rise higher; and so he grows, like a flourishing palm tree, from virtue to virtue, and by these virtues his righteous faith is exalted and adorned as bulwarks do a city.”
Source: St. Hildegard of Bingen, Hildegard of Bingen: Scivias (Classics of Western Spirituality (Paperback)), Paulist Press, 1990.