Paul Anton de Lagarde (1827-1891) taught at the University of Göttingen from 1869 to 1889, and was a correspondent of Masaryk in the 1880s. Masaryk remained concerned with Lagarde’s teaching, even after his death in 1891, until the end of his own life. Masaryk’s relationship to Lagarde was not only complex, but also highly paradoxical in view of Masaryk’s own reputation for humanitarianism and tolerance, which may explain why scholars have shied away from the topic. Lagarde tended to appeal to radical nationalists in Germany, eventually including Hitler’s National Socialists, by his avid promotion of the German mission of colonization in the East and his sharp critique of Jewish influences in Christianity. The key to understanding Lagarde’s attractiveness for Masaryk is the latter’s search for a religious dimension to round out his own Weltanschauung. Initially, there could be a rapprochement on the grounds of Lagarde’s reduction of Christian religion to an inner ethical voice, which Masaryk felt was compatible (in its absence of dogma or historical narrative) with his own rationalist theism. Ultimately, however, the two thinkers grew out of two contrasting albeit both Central European strands of thought, Lagarde from the idealistic and ontically monistic school, Masaryk from the realistic and ontically pluralistic one. The former trend, known as the German philosophical tradition, had its source in the secularized Lutheran subjectivism, the latter trend, known as the Austrian philosophical tradition, had its source in the Josephist Catholic Enlightenment with its empirical objectivism. In the end the metaphysical divergence made itself felt in the stark contrast between Masaryk’s humanitarian cosmopolitanism and Lagarde’s nationalist xenophobia. This led to Masaryk’s repudiation of Lagarde as a political pace-setter, despite a residual respect for Lagarde as a theologian. The story of their encounter sharply illustrates the difference of the two philosophical traditions in their bearing on the genesis of nationalism in Central Europe.