This work investigates the fundamental necessity of interior life and contemplative prayer as the essential foundation for all effective apostolic activity. Dom Jean-Baptiste Chautard, a Cistercian abbot, draws upon his extensive experience in monastic life to argue that external works of charity and evangelization are hollow if not fueled by a deep, sustained union with God. He presents a rigorous framework for balancing active service with the interior silence required to maintain spiritual integrity.

This text is widely regarded as a classic of twentieth-century spiritual literature, frequently cited for its uncompromising focus on the necessity of prayer in the life of the active apostolate. The work is characterized by its dense, traditional theological rigor and its direct, challenging tone aimed at those engaged in religious or charitable service.