In 1885 he entered the Conservatoire de Paris, studying under Théodore Dubois, then Jules Massenet, where he became a close friend of the young Georges Enesco.
He also founded the season of symphonic concerts with the newly created orchestra of the Conservatory, ancestor of the Orchestre symphonique et lyrique de Nancy.
In the early stages of World War I his friend and fellow composer Albéric Magnard was killed defending his house from German invaders.
At the same time he undertook the direction of the Philharmonic Orchestra of Strasbourg, influencing young students like Charles Munch.
However he self-identified as a Celtic Breton, writing that he was the son of a country "where the goblins populate the moor and dance by the moony nights around the menhirs; where the fairies and the enchanters - Viviane and Merlin - have as a field the forest of Brocéliande; where the spirits of the unburied dead appear all white above the waters of the Bay of the Departed.