Drawing from archival documentation of their long-standing literary relationship, this essay examines the correspondences between the negritude writings of Léopold Sédar Senghor and the assimilationist thought of his literary precursor René Maran. It traces the history of Senghorian negritude as a theory of cultural intermixture or métissage. As Fabre demonstrates, Senghor's ideas about the ethical and political significance of cultural hybridity, which emerged from his intellectual relations with transnational black figures of the 1920s and 1930s, aimed to counter biologically-rooted forms of racial essentialism with a notion of blackness—what Senghor referred to as the "black soul"—considered as a set of cultural properties.