Liberalism, with cosmopolitanism as its intellectual spearhead, seems to be in retreat, while illiberal and populist narratives have come to dominate the digital space. In this book, Detlef von Daniels suggests that this crisis can be addressed through historically situated self-reflection. It begins by noting that cosmopolitan ideas have antecedents going back to the pre-Platonic Sophists. In this light, Plato emerges as the first anti-cosmopolitan philosopher. Unsurprisingly, Plato again plays an important role in today's authoritarian discourses. Kant's political philosophy is then read as a fundamental reorientation of philosophy, though one whose dialectics Kant himself had already discerned. Against Heidegger's appropriation of both antiquity and Kant, Kelsen's theory of law emerges as a sober antidote that gives rise to two models of post-foundational thought. Framed by the voices of Sappho and Hölderlin, the book finally reveals a poetic mode of communication across space and time.