Marmion was born on 1 April 1858, the seventh child of William Marmion and his French wife, Herminie. Baptised Joseph on 6 April in St Paul’s Church, Arran Quay, his early life was passed entirely inside a few square miles of his native Dublin. The Marmion household was devoutly Catholic and three of Marmion’s sisters later entered the Congregation of the Sisters of Mercy. In 1868 he attended the primary school run by the Augustinian Friars in St John’s Lane, Dublin, before proceeding, in January 1869, to the Jesuit-run Belvedere College, where he received an excellent grounding in Greek and Latin. In 1874, at the age of fifteen years and nine months, he entered Holy Cross College, Clonliffe, the Dublin diocesan seminary, and commenced his studies for the diocesan priesthood. In 1877, having completed his studies in philosophy, he was conferred with the Bachelor of Arts degree by the Catholic University, Dublin. In 1879 he proceeded to Rome to complete his theological training living in the Pontifical Irish College and studying at the College of Propaganda Fide for eighteen months. Here he was recognised as a brilliant student, being awarded the gold medal for academic excellence in 1881. Although invited by the college authorities to present himself for the doctorate programme, he turned the offer down for health reasons, on account of the extra year in Rome that this would have entailed. He received minor orders in February 1881, was ordained subdeacon on 12 March, deacon on 15 April and, at the early age of twenty three years and two months, was ordained priest on 16 June.
It was while he was a student at Rome that Marmion felt for the first time the call from God to the Benedictine life. On 25 October 1886 Marmion received permission to join the Benedictine Order from Dr William Walsh, the newly appointed Archbishop of Dublin. On 21 November 1886 he entered the newly founded Belgian abbey of Maredsous, with which, by virtue of his Benedictine vow of stability, he was to be associated for the rest of his life. His writings, especially his Christ the Life of the Soul, show the reader how to become transformed into Christ. The third and final phase of his monastic life began when the Chapter of Maredsous elected him as its third abbot in 1909. He died at Maredsous on Tuesday 3 January 1923 after a brief illness which originated in a chill and developed into bronchial pneumonia. He was beatified by Pope John Paul II on 3 September 2000. – catholicireland.net