In order to see that a thing is only possible as a purpose, that is, to be forced to seek the causality of its origin not in the mechanism of nature but in a cause whose faculty of action is determined through concepts, it is requisite that its form be not possible according to mere natural laws, i.e. laws which can be cognised by us through the Understanding alone when applied to objects of Sense; but that even the empirical knowledge of it as regards its cause and effect presupposes concepts of Reason.
