Mary was born May 28, 1886, the daughter of Alex and Martha Thompson Wethington of St. Joseph, Ky. She was in her early twenties when she entered the novitiate at Mount Saint Joseph. Following a two‑month postulancy, Mary received the Ursuline habit and the name Sister Robertus on July 14, 1909.
Sister Robertus’ first assignment was St. Romuald School in Hardinsburg, Ky. Later assignments took her to other schools in Kentucky: New Haven, St. Charles, Fredericktown, Fairfield and from 1939 to 1958, Mount Saint Joseph Junior College and Academy. As an educator, she tried to lead students to an understanding that equality of all persons is designed by God as the keystone of a just human society. She challenged the denial of education for African Americans and stressed the evils of all forms of racial discrimination and prejudice. Her composition, Three Worshippers at the Crib, is a touching tribute to her years of work for social justice.
Beginning in 1951, Sister Robertus began researching the Ursuline community’s history, especially as it pertained to Mother Aloysius Willett. In 1970, Sister Eugenia Scherm used that historical information to write the definitive book on Mother Aloysius, Born to Lead.
Following a series of falls in March of 1963, Sister Robertus was hospitalized for observation. The physician diagnosed her suffering as adenocarcinoma, particularly to the brain, and gave a life expectancy of four months or less. Sister Robertus spent her final months in the infirmary and died on June 19, 1963. Following the funeral Mass, Sister’s remains were buried in the convent cemetery.
Sister Robertus was the first Mount Saint Joseph Ursuline to be buried in the modified headdress. Her two Ursuline sisters, Sister Augustine and Sister Richard, preceded her in death.