A scholarly biography of Jean‑Jacques Olier (1608‑1657), the founder of the Society of Saint Joseph and a pivotal figure in the French Catholic revival of the 17th century. Written by Bernard Pitaud, the book traces Olier’s early life, his spiritual formation, and his role as a spiritual director and reformer. It examines his influence on the Jesuit order, his pastoral work in Paris, and his lasting legacy in French religious history. The narrative blends rigorous historical research with accessible prose, making it suitable for both academics and general readers interested in ecclesiastical history.