The motu proprio of Bl. Pius X (22 Nov. 1903) directed his activity to Gregorian chant, under the guidance of Fr. Mauro Sablayrolles. In 1915 he was appointed prior of Montserrat, and had already published in the Rivista Montserratina, in Vida cristiana and in other Spanish journals numerous articles on Gregorian chant and liturgy. For the organization of the Gregorian movement he visited many Spanish seminaries and convents, and in 1905 published a Metodo di canto gregoriano which went through many editions and translations into foreign languages. MOQUEREAU, ANDRÉ (v.), he wrote in Catalan the Introduzione alla paleografia musicale gregoriana (1925) in which he set out the principles necessary for the study of manuscripts. This work was greatly expanded and updated in the French translation of 1935.
In 1931 he was called by Card. Schuster to direct the Scuola superiore di musica sacra in Milan, then newly founded, and during the seven years he spent there he worked indefatigably for the restoration and dissemination of Ambrosian chant, seeking out its manuscripts, photographing them and furnishing them with extensive critical studies. In 1934 he published the Exultet ambrosiano, in 1935 the Messa dei defunti and the Antiphonale missarum, in 1939 the Vesperale. In 1938, upon the death of Abbot Ferretti (v.), he was called to direct the Pontifical Institute of Sacred Music in Rome and devoted himself to a more scientific and modern organization of the Institute and its library, also writing numerous articles on the history of Gregorian chant. He collaborated on the first four volumes of this Enciclopedia Cattolica. On 14 Sept. 1942 he had been appointed titular abbot of S. Cecilia in Montserrat.