Lukács’ often-cited reproach to the Frankfurt School-that it was living in “the Grand Hotel Abyss (Abgrund)”-inadvertently raises the question of the ultimate “ground” or “foundation” of Critical Theory. By reflecting on the contingent, uneven, and even contradictory origins of the Institute for Social Research in Weimar Germany, the chapter addresses the theoretical issue of groundlessness as a paradoxical point d’appui for their work. Focusing on the often neglected importance of Schelling, it argues that Critical Theory explicitly eschewed what Adorno damned as “foundations mania” and derived its normative force from the possibility of a future emancipated society rather than a moment of unity or wholeness prior to alienation or reification.