 The German Metaphysics was Wolff’s next major philosophical text, and in it he formally introduces the division of metaphysical topics into ontology, cosmology, empirical and rational psychology and natural theology, a division that Kant, among others, would subsequently take up. The initial chapter attempts to make evident, in a Cartesian vein, both an indubitable truth (“we are certain that we exist”) and to establish a canon for what will count as a certain cognition for the remainder of the enterprise. In the second chapter Wolff sets out the two (Leibnizian) principles governing his philosophical thought: the principle of contradiction (“something cannot both be and not be at the same time” GM §10) and the principle of sufficient reason. Significantly, Wolff suggests that while the first is self-evident, the second admits of proof, for which Wolff (in a departure from Leibniz) offers two arguments. The first proceeds as follows: