Mann sketches his characters by pitting them against each other rather than by describing them directly. Naphta is characterized in terms of his intellectual adversary Settembrini. Naphta's intellectual prowess matches that of the Italian, but his cast of mind is essentially irrational. Whereas in Settembrini's view death is but the absence of life, Naphta insists that death controls a realm of its own; independent of life, death is engaged in perennial battle against it. His dualism is therefore the basis of his glorification of disease, suffering, and death. His love of extremes and contempt for all forms of compromise make him defend the Inquisition and the authoritarian aspects of Catholicism and communism.
As the antithetical element to Settembrini's rationality, Naphta replaces Clavdia Chauchat after Walpurgis Night. He takes over as the chief contestant for Castorp's soul on the side of irrationality.
He is of Jewish-Polish background and the product of Spanish Jesuit schooling. This is as significant as Settembrini's Italian descent. "Spain. That country too lay remote from the humanist mean," Castorp muses upon hearing of Clavdia's plan to travel to Spain, "though on the side of austerity rather than softness. There death was present in the guise of form, not dissolution — black, refined, sanguinary, Inquisition, stiff ruff, Loyola; he wondered what Frau Chauchat would say to Spain. Perhaps a combination of the two extremes would bring her closer to the humane mean." But then comes the seamy side of that coin: "Yet something pretty awful might come to pass if the East went to Spain." Naphta, then, is characterized as even more dangerous than Clavdia Chauchat because he is the result of "Eastern" irrationality and the sterile Spanish overemphasis on rigid form.