1. Metaphysics, the word xuan here, originates from a sentence in "Laozi": "Mysterious is mysterious, and it is the door to all mysteries."

2. Metaphysics is originally a term in Taoist (Taoist) philosophy, referring to a philosophical trend that emerged in the Wei and Jin Dynasties with "Laozi" as the core of its research.

3. Metaphysics is also called New Taoism, also known as metaphysics.

4. Metaphysics is a category of primitive philosophy, which refers to speculation about the nature of the invisible world that cannot be proven. The way of thinking that we often say observes things from an isolated, static, and one-sided perspective is a later extension. .

5. It is an ontological system for studying existence. Its theoretical principle is Plato’s dualization of the world, which historically served theology.

6. It has been used as a philosophical term since the 13th century to refer to the study of super-empirical things (soul, freedom of will, etc.).

7. Ontology, a branch of metaphysics: exploring the so-called ultimate reality beyond objective existence and beyond all phenomena.

8. For example, ontology can study the properties of an arbitrary object in any world.

9. Ancient cosmology: Explore issues such as the generation and change of the universe, and the structure of space and time.

10. Ancient cosmology has long been replaced by modern cosmology.

11. Metaphysics: Using non-scientific means to speculate on the origin, evolution and nature of life, as well as the relationship between life, the universe and ultimate reality.

12. For example, the often-said unity of nature and man falls into the category of this kind of discussion.