§ 40. The truth or the objective reality of the concepts that are used in metaphysics cannot be discovered or confirmed by experience. Metaphysics is subjectively actual because its problems occur to everyone as a result of the nature of their reason. How, however, is metaphysics objectively possible? The concepts of reason are transcendent because they are concerned with the absolute totality of all possible experience. Reason doesn't know when to stop asking, "why?." Such an absolute totality cannot be experienced. The corresponding objects of the necessary Ideas of reason cannot be given in experience and are misleading illusions. Only through self–knowledge can reason prevent the consideration of the immanent, subjective, guiding Ideas as being transcendent objects.