The metaphysical disputes were overcome by philosophic science, which is the study of ideas or understanding, by arriving at a clear and plain theory of understanding, the demonstration of which I have here attempted. The faculty of understanding had been transmitted to us by our superstitious ancestors as a thing of another world. But the illusion of another world is a metaphysical one and led to disputes about the idea of being. The positive outcome of philosophy assures us and demonstrates that there is only one world, that this world is the essence of all being, that there are many modes of being, but that they all belong to the same common nature. Thus philosophy has unified the concept of being and overcome metaphysics and its disputes. Universal being has only one quality, the natural one of general existence. At the same time this quality is the essence of all special qualities. Just as the concept of herbs includes all herbs, even weeds, so the concept of being comprises not only that which is, but also that which is not, which was once upon a time and which will be in the future. To free the concept of being from its metaphysical disputes, is a very difficult thing for those who attribute an extravagant meaning to the first principle of logic which says: "Any subject can have only one of two radically different predicates, because it cannot be at the same time A and not-A." All previous science of understanding has really revolved around this statement. It is based on something plausible, but still more on misunderstanding. Only when we have become aware of what has finally been the outcome of the science of understanding, only when this statement is backed up by the positive product of philosophy, does this stubbornly maintained and much contested statement receive a lasting value by its just modification. In the first place, a "subject" is not a fixed, but a variable concept. In the last analysis, as we have sufficiently explained in this work, there is only one sole universal subject which is nowhere radically different. The first principle of the old and tried Aristotlean logic tells us that a man, a subject, who is lame cannot move about with alacrity. But I have a friend who was totally lame and who today jumps about briskly; there is no contradiction in this. But if I tell another man about my lame friend and in the course of my story have this lame subject all of a sudden jumping over chairs and tables, then such a thing is _inconceivable_ and I contradict myself. Such a contradiction is a violation of all logic, but not because agility and lameness are totally different predicates which cannot be attributed to the same subject, nor because the contradiction cannot exist. Being is full of contradictions, but they are not simultaneous or without mediation. A logical speech or story must not forget to mediate. By mediation, all contradictions are solved. And this is the outcome of philosophy.