At the Abbey of Maredsous (1884–90) he completed his advanced studies and received the religious habit on 8 September 1890. In Rome he made his solemn profession on 25 December 1894, and on returning to Maredsous he was ordained priest in 1897 and devoted himself to philosophical studies, which he completed in Rome. From 1897 to 1909 he taught at the Pontifical Greek College, and from 1909 to 1918 at Maredsous. Returning to Rome in 1918, he again taught at the Pontifical Greek College, served as bursar of the Pontifical Commission for the Vulgate, and from 1920 also as procurator general of the Belgian Congregation of his Order. In 1923 he was appointed consultor to the Congregation for the Eastern Churches and in 1937 to the Congregation for the Propagation of the Faith; he was also a member of various commissions. In 1939 he was named archimandrite by the Melkite Patriarch of Antioch.
A scholar of Eastern disciplines, he made many journeys to the East to acquaint himself at first hand with the people and things that were the object of his studies. The fruit of these travels are the important articles he published in various journals. His principal works include: Leone XIII e la Chiesa greca (Rome 1904); L’inno aciathito, studio storico letterario (ibid. 1906); Genèse, source et division du texte grec de la liturgie de St Jean Chrysostome (ibid. 1908); Voyage de deux bénédictins au Mont Athos (Lille 1908); Le Collège Grec Pontifical de Rome (Rome 1910); Riti e particolarità liturgiche del Triodio e del Pentecostario (Padua 1947); Studi sui Sacramenti amministrati nel rito bizantino (Rome 1947); De monachico statu secundum byzantinam disciplinam (in Fontes Juris Can. Orientalis [Vatican City 1947]); Etudes sur la théologie orthodoxe (4 vols., Maredsous 1947–50). He was an active contributor to the Enciclopedia Cattolica on Eastern liturgy.