Léonie Aviat was born on September 16, 1844 in Sézanne, Marne, Kingdom of France. Her parents were shopkeepers in the town.
As a child, Léonie attended a convent boarding school run by the Visitation Sisters. There, she came in contact with two people who profoundly influenced the course of her life: Mother Marie de Sales Chappuis, the superior of the school, and Fr. Louis Brisson, the chaplain who in time founded the Oblate of St. Francis de Sales.
Léonie’s parents wanted the best for their daughter, and they hoped that she would marry a rich man they knew. Léonie, however, believed God wanted her to become a religious sister. After making a spiritual retreat in 1866, Léonie asked Mother Marie de Sales and Fr. Louis to help in her discernment process. They both advised her, at that time, to wait for a while.
During this waiting period, Léonie visited a factory that made and repaired reading glasses. As watched the workers, she felt a call to one day counsel and guide them to God and affirm the importance of their work.
Meanwhile, Fr. Louis saw many people from the rural areas of France who flocked to the factories and textile mills. Often, the workers were homeless and suffered all the problems related to homelessness. Fr. Louis’ observations led him to think of founding a religious congregation to assist the workers. After consulting Léonie to see if she would help him, Léonie agreed. With her friend Lucie Caneut, a former boarding school companion, Léonie began her journey to religious life on April 11, 1866. Fr. Louis, and Léonie, are honored as the cofounders of the Oblate Sisters of St. Francis de Sales on October 30, 1868. The primary purpose of the order was to provide education of girls, especially poor girls.
On October 30, 1868, as they received the habit of the new order, Lucie Caneut became Sister Jeanne-Marie, and Léonie became Sister François de Sales. Sr. François de Sales served as superior general twice.
On December 26, 1913, Sr. François became bedridden with a high fever that worsened. She died on January 10, 1914 of bronchopneumonia. Pope John Paul II canonized Léonie Aviat on November 25, 2001. Saint Léonie Aviat’s feast day is January 10.