In this work the author further elaborates on the ideas, to which he had given an introduction in his Groundwork of the Metaphysics of Morals, and which at the same time can serve as a brief outline of his doctrine of morals, insofar as he here thoroughly deals with the following questions: whether and in what way pure reason is practical, whether it has any relation to the faculty of desire, what kind of relation this is, and how we can conceive of the relation as possible and actual.