If we cannot say or settle anything certain about these questions on the basis of our own concepts, then we must not pass the blame on to the subject matter,b as hiding itself from us; for such a subject matter (because it is encountered nowhere outside our idea) cannot be given to us at all, but rather we must seek the cause in our idea itself, as a problem permitting of no solution, about which, however, we stubbornly insist on an actual object corresponding to it.