Now Kant explains the necessity and general applicability of the pure sense and mind conceptions by the fact that they arise from the organization of our mind. Accordingly, the world appears to the senses as a succession of phenomena in time and space. Our reason transforms these phenomena into things which are welded into one aggregate nature by laws of cause and effect. On the things as they really are in themselves, in the opinion of Kant, these pure conceptions cannot be applied. We know nothing of them and can neither perceive nor reconstruct them by reason, because "in themselves" they are wholly beyond reason and knowledge. The result of this investigation, which was the first valuable contribution to a scientific theory of understanding and forms, from our standpoint, the most important part of Kant's philosophy, served him mainly as a means of answering the following questions: What is the value of knowledge which exceeds experience? Can we, by mere deduction through concepts which go beyond experience, arrive at truths? His answer was: No, and it was a crushing blow to rationalism. We cannot exceed the boundaries of experience. By experience alone can we arrive at science. All supposed knowledge about the unlimited and infinite, about concepts of pure reason, called Ideas by Kant, (as the soul, the world, and God) is nothing but illusions. The contradictions in which the human mind becomes involved whenever it applies the categories outside of experience to such subjects, are manifested in the fruitless strife between the philosophical systems. Metaphysics as a science is impossible.