[3] In 1573 Barrière, having decided to introduce a reform into his abbey, became a novice there himself, and after obtaining the necessary dispensations, made his solemn profession and was ordained priest, some time after 8 May 1573.
The twelve monks at Les Feuillants, despite the example and exhortations of their abbot, refused to accept the reform, which they disliked so greatly that they tried to poison him.
Jean lived a patient, compassionate life and adopted routines such as sleeping on the floor with a stone pillow and eating without tables.
In 1581 Barrière received from Pope Gregory XIII a brief of commendation and in 1589 one of confirmation, which established the Feuillants as a congregation separate from the Cistercian order.
In 1598, Caterina Sforza di Santafiora, niece of Pope Julius III, had San Bernardo alle Terme built for the Feuillants.