It is beyond doubt that all knowledge begins with experience. - Immanuel Kant

things which as effects presuppose others as causes cannot be reciprocally at the same time causes of these.

But freedom is a mere Idea, the objective reality of which can in no wise be shown according to the laws of nature, and consequently not in any possible experience; and for this reason it can never be comprehended or understood, because we cannot support it by any sort of example or analogy.

Handle nur nach derjenigen Maxime, durch die du zugleich wollen kannst, dass sie ein allgemeines Gesetz werde.