How to understand metaphysics? What is the opposite?

Two basic meanings, such as a ruler inserted in the water, your eyes see that the ruler is bent. However, your knowledge about rulers and your optical knowledge tell you that rulers are not curved, but straight. You see it is curved because of the refraction of light. This is where you see the essence through the phenomenon. Metaphysics refers to looking at things from an isolated, static, one-sided and superficial point of view. Because, we can think, when we look at the world with our own senses, is this world, like the rulers, not presenting its essence to us correctly? We only see the appearance of this world without understanding or misunderstanding its essence? Therefore, the research object of metaphysics is the essence of the world. There are various answers to this question, such as: the essence of the world is matter, the essence of the world is a certain concept and spirit, the world flows out from God, and so on. This is called "ontology", a narrow sense of metaphysics. To the previous question, someone replied, "We have the ability to study the nature of the world." Some people say, "We don't have this ability." (agnosticism) For the latter question, some people argue that the essence of the world must be understood through rational logical deduction (rationalism), while others argue that it must be grasped through intuitive experience (empiricism). This is "epistemology", and metaphysics in a broad sense should include ontology and epistemology. Broadly speaking, the study of knowledge beyond perceptual experience can be called metaphysics. And the metaphysical definition given at the beginning refers to this. "Truth" refers to the essence of things that are covered by phenomena (there is no unclosed essence, so it is not appropriate in essence, so it is easy to understand here), and people know the essence of a thing through its phenomena. However, human understanding is developing, and many "realities" recognized in the past have been proved to be just phenomena by new scientific discoveries, so people must think about whether there is ultimate reality in a thing. Some people think that there is ultimate reality, that is, the principle of the world has been determined in advance; Others think that knowledge is constantly developing and there is no ultimate reality. In addition, if there is ultimate reality, it is also a question whether human beings can master this ultimate reality. Mastering it means mastering the fundamental laws of the universe, and fortune-telling is scientific. So, in short, it can be said that metaphysics is the study of nature. It is higher than physics, which studies phenomena and laws, and metaphysics studies its existence and essence. Second, in the works of Engels, Lenin and Mao Zedong, "metaphysics" has another meaning. Let's start with an old question: which came first, the chicken or the egg? The scientific answer is: in this world, chickens are not always like this, and they are not always like this. But in the long process of biological evolution, this form has gradually formed. This jumps out of the thinking cycle of either/or, completes a "unity of opposites" and solves this problem. The traditional way of thinking is called "intellectual thinking" or "formal logic thinking". Thinking about a problem with this kind of thinking is bound to fall into the dilemma of "chicken or egg first" and get contradictory and chaotic answers. In Critique of Pure Reason, Kant put forward four famous antinomies (that is, the question of "which came first, the chicken or the egg", whose characteristic is that his two opposite answers can be fully proved) and pointed out this question. He attributed this problem to the fact that human reason cannot understand the objective world. On the other hand, Hegel opposed Kant's view of unknowability. He suggested that if you jump out of the thinking cycle of either/or, you will not fall into contradictions and chaos. This is dialectics. Engels called the "intellectual thinking" as opposed to dialectics "metaphysics". Lenin and Mao Zedong also used this usage. Therefore, China's political textbooks give a second explanation of "metaphysics". However, when academic circles use the word "metaphysics", they usually take the first meaning. In fact, there is no difference between these two seemingly unrelated meanings of metaphysics. If we study the existence itself according to the traditional metaphysical method without considering its external and temporary superficial phenomena, researchers will easily fall into isolation and one-sidedness. Because it is obvious that a society without people is not a society, and people without society are not people. Anyone who wants to study the essence of society without "people" can only get isolated, static and one-sided (that is, the second meaning of metaphysics).