In Baptism, the Lord makes us not only persons of light, but also sources from which living water bursts forth. We all know people like that, who leave us somehow refreshed and renewed; people who are like a fountain of fresh spring water. We do not necessarily have to think of great saints like Augustine, Francis of Assisi, Teresa of Avila, Mother Teresa of Calcutta and so on, people through whom rivers of living water truly entered into human history. Thanks be to God, we find them constantly even in our daily lives: people who are like a spring. Certainly, we also know the opposite: people who spread around themselves an atmosphere like a stagnant pool of stale, or even poisoned water. Let us ask the Lord, who has given us the grace of Baptism, for the gift always to be sources of pure, fresh water, bubbling up from the fountain of his truth and his love!
Benedict gives four examples of "great saints," of which one is Mother Teresa, who isn't even canonized (she was beatified in 2003). Pretty rarefied air for the little nun from Albania.