no cognition whatever is possible of the supersensible in this way (of natural concepts). The ground of its success by the moral way (of the concept of freedom) is as follows. Here the supersensible (freedom), which in this case is fundamental, by a determinate law of causality that springs from it, not only supplies material for cognition of other supersensibles (the moral final purpose and the conditions of its attainability), but also establishes its reality in actions as a fact; though at the same time it can furnish a valid ground of proof in no other than a practical point of view (the only one, however, of which Religion has need).

It is thus very remarkable that of the three pure rational Ideas, God, freedom, and immortality, that of freedom is the only