Mother Teresa, who was canonized as St. Teresa of Calcutta in 2016, died on Sept. 5, 1997, at the age of 87.
Her final letter to the Missionaries of Charity – the religious community she founded – was written on the morning of her death. Today, it is part of the Office of Readings. It is read and reflected on as part of the liturgy of the hours for Sept. 5 each year.
In the letter, Mother Teresa provided a snapshot into her spiritual life in what would be the waning hours of her life and gave a message to her community about her excitement for the future.
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"In her last letter, Mother Teresa sums up much of her life's work, by looking at it through the lens of the Virgin Mary," Fr. Patrick Mary Briscoe, O.P., a Washington-based Dominican friar, told Fox News Digital this week.
"Is it any surprise that the saint, who was a mother who loved so many, would honor and imitate so closely the mother of Christ?"
Addressed to "her dearest children," Mother Teresa encouraged those in her community to "be only all for Jesus through Mary."
In Catholicism, Mary is venerated, as without Mary, there would be no Jesus.
By the nature of being Jesus' mother, she had a relationship with Him that was unlike any other.
"No one loved or served Jesus better in this life than Mary," Fr. Jeffrey Kirby, a priest of the Diocese of Charleston, told Fox News Digital.
"Mother Teresa, therefore, points us to Mary and calls us to imitate her faith, selfless service, love and cheerfulness."
The imitation of Mary's faith and deep love for Christ is "all Mother wants for you, all Mother wants from you," she wrote.
"If in your heart you are only all for Jesus through Mary, and if you do everything only all for Jesus through Mary, you will be a true Missionary of Charity," she said.
Mother Teresa wrote that her order has "much to thank God for, especially that He has given us Our Lady's spirit to be the spirit of our society" and reminded them that so much of their lives is saying "yes" to Jesus "and running in haste to serve Him in the poorest of the poor."
She then reflected on the upcoming anniversary of her inspiration to found the Missionaries of Charity and was thankful for all that was done in those years.
"Let our gratitude be our strong resolution to quench the Thirst of Jesus by lives of real charity: love for Jesus in prayer, love for Jesus in our Sisters, love for Jesus in the poorest of the poor. Nothing else," she said.
Mother Teresa's condition took a turn for the worse, and she died before she could sign the letter, Sister Nirmala Joshi, Mother Teresa's successor as the superior general of the Missionaries of Charity, wrote underneath it.
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"This is the last letter of Our Mother which was ready for her signature. But Jesus came to take away Our beloved Mother so suddenly that is remained unsigned," wrote Sister Nirmala Joshi.
"I am sending this to you with great love. This is our Mother's last message to us. Let us take it to our hearts with much love and prayer."
Born Agnes Gonxhe Bojaxhiu in what is now known as Skjope, North Macedonia, Mother Teresa was of Albanian heritage, according to the website for the Nobel Peace Prize.
First feeling the call to religious life during her adolescence, she left home in Sept. 1928 at age 18 and moved to Ireland, joining the Sisters of Loreto.
With the Sisters of Loreto, the teenage Agnes was given the religious name "Sister Mary Teresa," in honor of St. Thérèse of Lisieux, the Vatican's website stated.
A little more than a year after her arrival in Ireland, she was sent to one of the Sisters of Loreto's missions in India, a country that would become her adopted homeland.
She made her first profession of vows in May 1931 and was assigned to the Sisters of Loreto's community in Calcutta, according to the Vatican's website.
She professed her final vows with the Sisters of Loreto in 1937 and became known as "Mother Teresa."
In 1948, Mother Teresa would leave the Sisters of Loreto to begin working on founding a new religious order, the Missionaries of Charity.
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"On Aug. 17, 1948, she dressed for the first time in a white, blue-bordered sari and passed through the gates of her beloved Loreto convent to enter the world of the poor," said the Vatican's website.
Just over four months later, Mother Teresa first encountered what would be the rest of her life's work.
"On 21 December she went for the first time to the slums. She visited families, washed the sores of some children, cared for an old man lying sick on the road and nursed a woman dying of hunger and TB," according to the Vatican's website.
In 1950, the Missionaries of Charity was officially approved to operate within the Archdiocese of Calcutta.
"Our community is totally dedicated to the service of the poorest of the poor, irrespective of social class, creed or color," according to the order's website.
"We deliberately choose to show God's concern for the poorest and the lowliest, remaining right on the ground, while offering immediate and effective service to those in need, until they can find someone who can help them in a better and more lasting way."
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Today, the Missionaries of Charity are found throughout the world and have more than 5,000 members.
