Time raises certain irresolvable contradictions: the question of its absolute beginning leads us into the paradox of infinite regress versus a 'time before time', and to conceive of the temporal present as either an extension or a simple point fails to explain how time passes now. In this book, James Sares demonstrates - via his readings of Kant and Hegel - that time cannot be. His approach to the reality of time stresses the irreducibility of the contradictions that confound the conceivability of its very existence. Sares' approach is both exegetical and critical, developing textual analyses of Kant and Hegel's respective claims concerning the antinomies of time while challenging and extending their work in conversation with contemporary debates in metaphysics and the philosophy of time. He rebuts Kant's suggestion that the arguments of his antinomies do not apply to time because of its status as an appearance, drawing on Hegel's dialectical logic to argue for the contradictoriness of this appeal. Yet Hegel, for Sares, fails to clearly articulate the irresolvability of the antimonies. He views the philosopher as denying time's relevance to the being of logical truth and hence his own logical system. He therefore critiques Hegel by returning to Kant, underscoring the importance of the antinomies as problems concerning the very possibility of worldly existence. Offering a rigorous defence of Kant's presentation of the antinomies, this book simultaneously challenges the purported rational closure of Hegel's logical system. As such, it constitutes a novel contribution to the scholarship on Kant, Hegel, and the philosophy of time.