Blessed Teresa of Calcutta’s private spiritual writings, consisting mainly of her letters to her spiritual directors, has now become a best seller, listed at No. 2 on last week’s New York Times best seller list. The book, entitled “Come Be My Light: the Private Writings of the Saint of Calcutta,” is edited by Father Brian Kolodiejchuk, MC, the postulator (or official advocate) of her cause of beatification and canonization. (Mother Teresa, who died just 10 years ago, has not yet been canonized. For that another miracle is needed. She was of course beatified in record time.)

The book has made quite a stir: It documents the extended “dark night of the soul” that Mother Teresa experienced virtually without intermission from the time of the visions and locutions that marked the beginning of her special vocation to serve the poorest of the poor, to the time of her death in 1997. For us superficially religious Americans, who are sometimes tempted to confuse warm and fuzzy feelings with living the faith and following Christ, her writings are a stark reminder of the centrality of the cross in the Christian life. Of course, the saints and mystics like St. Teresa of Avila, St. John of the Cross, and St. Therese of Lisieux (the Little Flower), all experienced something similar. “I’m OK, you’re OK” doesn’t begin to capture the demanding drama of the spiritual life.

In other areas of our life, to be sure, we know that achievement and accomplishment have a steep price tag. If we want to lose weight, for example, we need to watch what (and how much) we eat. If we want to excel at sports, we need to train and exercise ourselves with some regularity. The same goes for playing music or becoming a lawyer. We need to work at it. “Practice makes perfect,” and it should not be surprising that the same holds true for the spiritual life. If you want to be a saint, and Vatican II said God calls all of us to holiness, then you must work at it. The path necessarily involves renunciation and sacrifice: “If anyone wants to come after me, he must deny himself, take up his cross, and follow me” (Mt 16: 24).

Christ’s blood was the price of our redemption. “You have been bought at a great price,” says St. Paul (1 Cor 6:20). Mother Teresa wrote, “The missionary must die daily, if she wants to bring souls to God. She must be ready to pay the price he paid for souls, to walk in the way he walked for souls” (p. 140). “The disciple is not above his teacher” (Mt 10:24), and so can we be surprised that people who do a great work for souls pay a high price?

Another popular modern saint, Padre Pio, canonized just five years ago (the same year as my personal favorite, St. Josemaria Escriva, the priest who founded Opus Dei and whom John Paul II called “the saint of ordinary life”), also gave striking testimony to the redemptive value of pain and suffering. For one thing, for 50 years, from 1918 until his death on Sept. 23, 1968, he bore the stigmata, the physical tokens of Christ’s wounds.

For another, Padre Pio’s correspondence with his spiritual directors, covering the years 1910-1922 (first published in English in 1980), reads much like Mother Teresa’s. He writes, for example, to his spiritual director in 1912, “Do not allow the idea of my sufferings to cast a shadow on your spirit or to sadden your heart. So let us not weep, my dear Father; we must hide our tears from the One who sends them, from the One who has shed tears himself and continues to shed them every day because of man’s ingratitude. He chooses souls and despite my unworthiness, he has chosen mine also to help him in the tremendous task of men’s salvation. ...This is the whole reason why I desire to suffer more and more without the slightest consolation. In this consists all my joy” (“Padre Pio of Pietrelcina, Letters: Vol. I,” p. 343).

These modern saints were willing to pay the price for souls -- our own included. Are we willing to do our small part, probably in ordinary life, most likely without the accompaniment of visions, locutions, stigmata or other extraordinary manifestations of the supernatural? After all, that seems to be what living from faith means.

Dwight Duncan is a professor at Southern New England School of Law. He holds degrees in both civil and canon law.