Kant, Hume, and the Interruption of Dogmatic Slumber offers an interpretation of Kant’s “confession,” in the Prolegomena, that “it was the objection of David Hume that first, many years ago, interrupted my dogmatic slumber.” It argues that Hume roused Kant not, as has often been thought, by challenging the principle “every event has a cause” that governs experience, but by attacking the principle of sufficient reason, the basis of rationalist metaphysics and of the cosmological proof of the existence of God. This proposal makes it possible to reconcile Kant’s declaration about Hume with his later assertion that it was the Antinomy of pure reason that first woke him from dogmatic slumber, because the Antinomy, like Hume’s challenge, is directed against the dogmatic use of the principle of sufficient reason. The proposal put forward here also makes it possible to understand why Kant speaks of “the objection of David Hume” after mentioning Hume’s attack on metaphysics; for the “objection” that Kant has in mind, it is argued here, is a challenge to metaphysics, rather than to the foundations of empirical knowledge. This work also leads to a new view of Hume himself—as primarily interested not in the foundations of experience but in the problem of metaphysics. It thereby lets us see both Kant and Hume as champions of the Enlightenment in its struggle with superstition.