Man and his understanding are progressive, and for this reason he must progress by experience in his classifications, conceptions, and sciences. The fixed, impregnable, socalled apodictical facts are nothing but tautologies, if seen at close range. After it has become common usage to call only heavy and tangible things bodies, it is an apodictical fact that all bodies are heavy and tangible. If the conceptions of vapor, water and ice are restricted by common usage and by science to the three stages of aggregation of the same substance, then we need not wonder at our firm assurance that the water will always remain fluid in all time to come, also above the stars. This signifies nothing more than that we conceive of the things as solid which we call solid, and of those as fluid which we call fluid, but it does not change the fact that our faculty of understanding or perceiving gives us only an approximate picture of natural processes, in which the solid and the fluid are neither wholly opposed nor different, but where the positive and the negative gradually flow into one another. The philosophers produced a very good conception of understanding by developing the concept of truth step by step and finally coming to quite exact results. But this "quite exact" must only be accepted in a reasonable sense, not in an extravagant one. Truth as the infinite, as the sum total of all things and qualities, is "in itself" quite right, but it cannot be accurately reproduced, not even by means of the mind, of reason, or understanding. The means is smaller than the purpose, is subordinate to purpose. So is our faculty of understanding only a subordinate servant of truth, of the universe. The latter is absolutely evident, true, indubitable, and positive. It does not vitiate the sublimity of this world in the least that it is veiled by appearances, by error, by untruth. On the contrary. Without sin there is no virtue, and without error there is no understanding, no truth. The negative, the weakness, the sin and error, are overcome, and thereby truth shines in full splendor. The universe, the general truth, is a progressive thing. It is absolute, but not at any fixed time or place, but only in the combined unity of all time and space. It is sometimes said that this is too much for our intellect, that we cannot understand this. It is true that we cannot squeeze this into any of our categories, of our fundamental conceptions, unless we place the category of illimited and indeterminable and infinite truth at the beginning of them. If that is not quite clear and plain, it should serve to teach us that the category of clear and plain human understanding is destined to recognize its function as a subordinate factor of nature.