In the Architectonic of Pure Reason, near the end of the Critique of Pure Reason, Kant declares: Nobody attempts to establish a science without grounding it on an idea. But in its elaboration the schema, indeed even the definition of the science which is given right at the outset, seldom corresponds to the idea; for this lies in reason like a seed, all of whose parts still lie very involuted and are hardly recognizable even under microscopic observation. (KrV, A834/B862) Here Kant suggests that any science (Wissenschaft) needs to be grounded on an “idea” – a concept of reason which helps to distinguish that science from others, and which makes possible the integration of a plurality of cognitions into a systematic whole. This means that natural science itself requires such an idea. Since Kant takes the Metaphysical Foundations of Natural Science (Metaphysische Anfangsgründe der Naturwissenschaft, MAN) to be a constitutive part of natural science, it is incumbent upon him to clarify the idea upon which it is grounded. This important task is carried out in the Preface (Vorrede) to MAN (4:467–79). While stating the task is easy, it took Kant great intellectual effort to complete it in his own characteristic way.