This essay analyzes the rhetoric of idealist Pan-Asianism in the literary and critical writings of a modern poet, Rabindranath Tagore, who was acknowledged worldwide in the early twentieth century for his good sense, good morality, and good will. Through his idealistic faith, based on his own idealist philosophy that viewed the world as a twin-pan balance, Tagore struggles to strike a blow against nationalism, imperialism, and materialism, and he shows his readers his ideal world: one in which “One Asia” and “One Europe”—the spiritual/soul and material/body—coexist in equality and peace. Rooted in his philosophical idealism, Tagore creates an advanced rhetorical logic that presupposes the Other coexisting with us from the beginning, instead of the rhetoric of exclusion and rejection. Therefore, his rhetoric appeals to the powerless rather than the powerful. However, his international target readers were dominant European, American, and Japanese intellectuals, and unfortunately, he did not receive emotional sympathy from his main audience. Through this failure of Tagore’s rhetoric, we can reaffirm the importance of pathos as much as of ethos and logos when idealism works as a rhetoric or a discourse.