Kant’s critical philosophy defines its main theoretical and practical areas of inquiry—the power of cognition and the power of desire—by conceiving of the idea of freedom as a limit. This essay explores how in being constituted by freedom the subject plays the function of the limit that enables theoretical thought. It examines the constitution of subjectivity from three different standpoints. “Incessant Perspective,” a reflection on art’s ability to signify what exceeds representation in Velázquez’s painting Las Meninas, underscores the productivity of self-consciousness but also on the optical illusion that allows self-consciousness to emerge. “Subjectivity at the Limit” turns to Kant’s third antinomy in the Critique of Pure Reason to examine the introduction of the idea of freedom as the limit that enables the smooth functioning of thought by bounding it. But explaining how freedom constitutes ethical subjects whose acts introduce freedom’s effects in the world lies beyond reason’s reach. “Trace of a Wandering Cause” explores the emergence of ethical subjectivity in Levinas’s Otherwise than Being. A rhetorical reading suggests that Levinas’s language performs the subjectivity as substitution his argument evokes. Here Kant’s theoretical and practical approaches to freedom meet. The ethical subject that emerges by substituting itself for the excess-other that constitutes it (freedom) is the same subject that from a theoretical perspective substitutes itself for the unconditioned cause (freedom). The concluding section, “Autonomy or Being Inspired,” defines autonomy with Levinas as believing oneself the author of a law one has received and saying it in one’s voice.