Maurice Leenhardt (1878-1954) was a missionary of the Société des Missions Évangéliques de Paris in New Caledonia and an ethnologist, friend of Lucien Lévy-Bruhl and Marcel Mauss. Although he belongs to the colonial world of the 1930s, he developed an original concept of Christian mission. Gilles Vidal intends to show how, for Leenhardt, spiritual conversion begins with a moral awareness that elevates all beings, regardless of their “race”, to human dignity. To this end, resources of the social sciences must be applied, making it possible to gain an authentic understanding of the culture of others. Leenhardt supports a humanist and idealist position that claims to discover the “soul” of the other, thus linking mission and colonisation “in harmonious fashion”.