Benedictine Father Wilfred (Robert John) Theisen, 95, died Dec. 3 in the retirement center at Saint John’s Abbey, Collegeville. The monks, family, and friends will receive the body at 7 p.m. Thursday, Dec. 5, and celebrate the Mass of Christian Burial at 9 a.m. Friday, Dec. 6, in the Saint John’s Abbey and University Church, with interment in the Abbey Cemetery. The service will be livestreamed on YouTube.
The sixth of nine children, he was born to John Franklin and Elizabeth Theresa (Tabery) in Wadena, on Sept. 5, 1929. At the age of four he lost his father whose death left his widowed mother with nine children — all under the age of 10.
Following graduation as valedictorian from Saint John’s Preparatory School in 1947, he was accepted that year as a freshman at Saint John’s University on a pre-divinity scholarship. Two years later, he entered the novitiate. He was given the name Wilfred and professed simple vows as a Benedictine monk in 1950 and final profession in 1953. After completing divinity studies at Saint John’s Seminary, he was ordained to the priesthood in 1956.
Father Theisen’s education continued with summer graduate work at the University of Colorado, Boulder, where he earned a master’s degree in physics in 1962. He then enrolled in a doctoral program at the University of Wisconsin, Madison, in 1966 and was awarded a doctorate in the history of science in 1972.
His teaching career began in the physics department at Saint John’s University in 1953. He resumed teaching again in 1962, followed by another 35 years in the classroom from 1970 to 2005. At the end of his teaching career, Father Theisen was awarded the title of Professor Emeritus of Physics by the SJU faculty.
He became the liaison officer for the Collegeville Institute for Ecumenical and Cultural Research in 1975, a position he held for 40 years. In addition, he worked as assistant director of Hill Monastic Manuscript Library at Saint John’s University and was part of the chaplaincy team that ministered to the Sisters of Saint Benedict’s Monastery, Saint Joseph.
Father Theisen punctuated his teaching career with two sabbaticals: one in Cambridge, England, and another in Oxford, England. His academic acumen was further reflected in National Science Foundation Summer Fellowships at the University of Chicago and Argonne Laboratory and a National Endowment for the Humanities Summer Fellowship at Harvard University.
He is survived by his sister-in-law, Marilyn (Lyle), and the community of Saint John’s Abbey.