Kant did not explain the method of his foundation of ethics expressly. However, we can comprehend it as the demonstration of the originality of morality. For morality cannot be derived from anything non-moral – such a relation of derivation would destroy it. Therefore, there cannot be a justification or proof of morality in the strong sense, there can only be a “groundwork”, as the term “Grundlegung” is normally translated in English. This groundwork or grounding consists in disclosing the place or topos and the turn or trope of its originating. According to Kant, the first is the will as practical reason; the latter is the turn of the will towards itself as autonomy. The result of such groundwork is, first, the evidence of the authenticity of morality and, hence, its unconditional validity – since such original validity is not conditioned on anything extra-moral. Second, we get a normative criterion for the contents of morality, which in Kant takes the form of the Categorical Imperative. The article seeks to defend the view that there is no alternative to Kant’s method of the foundation of ethics. However, by describing this method in a purely formal way, the author aims to open up the possibility to implement it in another way and with other results than Kant does.