The Groundwork of the Metaphysic of Morals is the first work in which Immnauel Kant speaks explicitly of conceptual 'transitions' from one domain to another. This chapter shall specifically discusses a transition occurred in the first section of the Groundwork (that is, from common moral rational knowledge to what Kant calls philosophical moral rational knowledge). The first transition possesses an essentially affirmative function: Kant shows that our common understanding of ethics corresponds precisely to what can in fact be formulated in terms of an a priori ethics. Common moral rational knowledge thus already possesses the fundamental concepts belonging to a genuine ethical philosophy. Philosophical moral rational knowledge expressly clarifies and develops these fundamental concepts in a positive relation to this common ethical thinking, and the metaphysics of morals subsequently provides a final and definitive analysis that specifies and differentiates these concepts in a critical relation to popular moral philosophy.