Dupré was the most gifted student of his generation. He studied the organ with Guilmant and Vierne, and composition with Widor who treated him like a son for the rest of his life. Barely twenty years old when he suddenly found himself Assistant Organist at St-Sulpice, Dupré was to continue playing the organ that was his greatest joy for the rest of his life. He wrote four choral motets during the First World War. O Salutaris Hostia is from the last two verses of Verbum Supernum, one of the five Eucharistic Hymns written by St. Thomas Aquinas, for the newly instituted Feast of Corpus Christi in 1264.