While no one knew it at the time, 1951 was a pivotal year for Mother Teresa of Calcutta, the start of a private battle for the tiny nun millions hailed as a living saint.
"When we talk about Mother Teresa we celebrate her victories and all the good works she accomplished in her life. But what did this victor have to overcome? That's an important question," said journalist Kenneth Woodward, author of "Making Saints: How The Catholic Church Determines Who Becomes A Saint, Who Doesn't, and Why."
"We often miss this spiritual warfare component in the lives of the saints, that whole element of struggle and grace. … With Mother Teresa, this just has to be there or her story is not complete."
It was in 1928 that 18-year-old Agnes Gonxha Bojaxhiu left her family in Macedonia to join the Sisters of Our Lady of Loreto, first working as a teacher in Calcutta.
Then, on Sept. 10, 1946, Sister Mary Teresa experienced a vision of Jesus calling her to move into the slums while serving the poorest of the poor. After this "call within a call" she created the Missionaries of Charity, beginning the work that produced waves of support for the Vatican to proclaim her a saint -- which will occur in rites on Sept. 4, the eve of the anniversary of her death on Sept. 5, 1997.
But another story was unfolding that remained a secret for decades.
It was in 1951 that Mother Teresa prayed that she be allowed to share the pain and loneliness that Jesus suffered on the cross. Her private letters made it stunningly clear that this prayer was granted. Her visions stopped, replaced by silence.
"Lord, my God, who am I that you should forsake me?", she asked her spiritual director in 1957. "The one -- you have thrown away as unwanted -- unloved. I call, I cling, I want, and there is no one to answer. … Where I try to raise my thoughts to heaven, there is such convicting emptiness that those very thoughts return like sharp knives. …
"I am told God lives in me -- and yet the reality of darkness and coldness and emptiness is so great that nothing touches my soul."
In addition to hearing glowing details about her work and self-sacrifice, it's crucial for Mother Teresa's admirers to learn about this "dark night of the soul," according to the popular Jesuit writer Father James Martin, author of "My Life With the Saints." The most powerful part of her story is that she remained faithful and continued her ministry.
News reports about her upcoming canonization skipped this crisis, but "I think that's likely because it's so confusing for people, and that many in the secular media wouldn't know what to make of her 'dark night,' " he said. In fact, when her private writings were first published, "most commentators completely misread it, and even concluded that she was an atheist."
Truth is, many saints experience similar spiritual challenges. But while other saints -- at least those who left journals -- described episodes in which they felt spiritually attacked, Mother Teresa's struggles appear to have lasted through the entire public ministry that made her famous.
In another letter, Mother Teresa reflected on the source of her suffering: "I am afraid I make no meditation, but only look at Jesus suffer and keep repeating: Let me share with you this pain! If my pain and suffering, my darkness and separation, give you a drop of consolation, my own Jesus, do with me as you wish.
"I am your own. Imprint on my soul and life the suffering of your heart. If my separation from you brings others to you … I am willing with all my heart to suffer all that I suffer."
Martin said the reality of this "dark night" experience should make her a uniquely appealing saint for those who doubt their faith and God's love for them.
"Many saints did what she did -- lead a holy life, work with the poor, found a religious order," he said. "None, however, as far as I know, did so facing complete interior darkness for such an extended period of time. That makes her, in my estimation, the greatest saint of modern times."