The beginning of the Transcendental Dialectic marks an important transition in the Critique of Pure Reason and in Kant's philosophical system as a whole. In approximately the first half of the Critique, Kant argues that we can have immanent metaphysical knowledge of synthetic a priori principles that structure all possible human experience, because they are grounded in our pure forms of intuition (space and time) and the pure concepts of our understanding (the categories). But Kant's argument for this immanent metaphysics rests on his claim that human knowledge can result only from applying concepts to intuitions, or more precisely to schemata mediating the application of concepts to appearances. This key claim implies that transcendent metaphysical knowledge - knowledge of objects that transcend the boundaries of possible human experience - is impossible for us, since it would involve deploying concepts independently of intuitions or schemata. If Kant had ended the Critique at this point, then his positive argument for an immanent metaphysics in the first half of the book would be wide open to attack from those unwilling to accept its strong negative implication that transcendent metaphysics is impossible. But as Kant was well aware, the Leibniz-Wolffian tradition that dominated German philosophy in the eighteenth century held that transcendent metaphysics is not only possible but actual.