Maréchal joined the Jesuits in 1895 and after a doctorate in biology at Leuven he first specialized in experimental psychology, spending some time in Munich with Wilhelm Wundt. Until the end of his life Maréchal would say that his real interest was more in psychology than in philosophy. Prompted by the call of Pope Leo XIII to revitalize Thomist theology, he started studying in depth the works of St. Thomas Aquinas in order to understand the inner coherence of his system, along with the works of other scholastic thinkers, modern philosophers and scientists of the day. From this, and in particular from Kant's transcendental idealism, emerged a new and more dynamic Thomism, recapturing the union of 'act and power' in Aquinas. The development of his thought can be grasped in the five cahiers in which, after exposing the weaknesses of traditional Thomism, he evaluated Kant's philosophy with whose help he proposes a modernized Thomism in the 4th and 5th cahier. The work of Maréchal had a great influence on such contemporary theologians and philosophers as Andre Marc, Gaston Isaye, :fr:Joseph de Finance|Joseph de Finance, Karl Rahner, Bernard Lonergan, :de:Johannes Baptist Lotz|Johannes Baptist Lotz, Bernard O'Brien and Richard De Smet. In the same way, he proceeded to study the psychology of the mystics. Until his death on 11 December 1944 he taught philosophy and experimental psychology at the JesuitHouse of Studies in Leuven. He was a great friend of Pierre Scheuer, the Belgian Jesuit who has been described as a metaphysician and mystic.
Main works
Le point de départ de la métaphysique: leçons sur le développement historique et théorique du problème de la connaissance, 5 vols,.
Études sur le psychologie des mystiques, 2 vols, Poona: De Nobili College, 1963–65. 1–37. Unpublished. Available at Jnana Deepa Vidyapeeth Library, Pune, N13/M332.
"At the Threshold of Metaphysics: Abstraction or Intuition?" Tr. Richard De Smet and others. Poona: De Nobili College, 1963–65. 38–149. Unpublished. Available at Jnana Deepa Vidyapeeth Library, Pune, N13/M332.
"The Natural Desire for Perfect Happiness." Tr. Richard De Smet and others. Poona: De Nobili College, 1963–65. 150–170. Unpublished. Available at Jnana Deepa Vidyapeeth Library, Pune, N13/M332.