Immanuel Kant long sought to write a metaphysics of nature. In a 1765 letter to Johann Heinrich Lambert, Kant reported that he was postponing the general project he had been working on, the “Proper Method of Metaphysics.” He would instead produce the paired “Metaphysical Foundations of Natural Philosophy” (metaphysische Anfangsgründe der natürlichen Weltweisheit) and “Metaphysical Foundations of Practical Philosophy” (der praktischen Weltweisheit) (Br, 10:56; see Förster 1989, 289–90) as particular examples in concreto of the proper philosophical methodology. Despite Kant’s claim that the “content” of these projects was “already worked out,” they were, in turn, deferred and subsequently shelved during his writing of the Inaugural Dissertation (MSI) and the subsequent tumult to his metaphysical outlook left in its wake. Nonetheless, Kant still harbored ambition to write a metaphysics of nature, expressing his hope to return to this project in the preface of the 1781 first edition of the Critique of Pure Reason while acknowledging that a critique of reason must antecede his metaphysical ambitions: “[The] Metaphysics of Nature … will be not half so extensive but will be incomparably richer in content than this critique, which had first to display the sources and conditions of its possibility, and needed to clear and level a ground that was completely overgrown” (KrV, Axxi). With the foundation for the metaphysics of nature thus laid bare with the completion of the Critique of Pure Reason, Kant embarked on writing the Metaphysical Foundations of Natural Science (Metaphysische Anfangsgründe der Naturwissenschaft), finally published in 1786, over twenty years after he mentioned the project to Lambert.