Mary Catherine Steil was born in Lancaster, Wisconsin on June 16, 1888. Her father was a native of Luxemburg, her mother, an American. Catherine entered at Clyde on Feb. 24, 1905 and received the Benedictine habit on Nov. 13 the same year. On Sept. 27, 1907 she was professed as Sister Mary Modesta, and made perpetual vows July 5, 1913.

Sister was at our Chewelah foundation from August, 1914 to April, 1927, with one year's intermission which she spent at Clyde. When this foundation was closed, she was transferred to the Mundelein community as one of its pioneer members. There she ably filled the office of infirmarian. However, in her earlier religious life she also taught at the Academy and was prefectress of the younger girls. During all her religious life, Sister was faithful, exact even to the minutest detail in her duties, patient, cheerful, always thoughtful of others. She was neat and orderly, very dependable.

On the 21st of September, Sister came by car from Mundelein with some of her companions who with her were preparing to celebrate their Golden Jubilee on the 27th. She had kept an hour of adoration at her loved sanctuary in Mundelein the night before, and during the trip to Clyde was bright and cheerful. But she seemed quite fatigued on her arrival at Clyde that evening. She complained of shortness of breath and a pain in the region of her heart. After a day's rest in the infirmary, it was decided to have her taken to the hospital at Maryville for a cardiogram. Tests showed a slight enlargement of the heart, but the doctor did not consider her condition serious and felt that with proper medication she would be able to "go to the altar for her holy vows." 

On returning to the convent on September 26th, 1957, Sister was so energetic that without asking the infirmarians she went to the adoration chapel and was in her stall for Vespers. After leaving the chapel she was warmly greeted by the Sisters, and was then taken back to the infirmary where one of her Jubilee companions spent the evening recreation with her. She was very joyful and interested in everything. All seemed well as the night nurse came on duty  but during the night the Divine Bridegroom came to claim His faithful bride, to celebrate her Golden Nuptials with Him in His kingdom. 

Though her celebration here below took the form of a requiem instead of a jubilee, it was nevertheless a joyous celebration, with Msgr. Meegan from Mundelein and several priests offering the Mass. Thus her life of faithful service, in the "splendor of the Eucharistic Sun" was crowned with joy as she lovingly and willingly gave back her life to God. Sister was seventy-one years old.