The four characteristics of impermanence are: born for many reasons. There is no such thing in this life, and there is death after this life. Birth, illness, death, migration, not permanent residence. Four stages (life, residence, dissimilarity and extinction). Like a dream bubble, like dew, like electricity. Refers to truth and vulgarity. These characteristics of impermanence have many reasons, which come together. There is a phenomenon of birth and death in a regular place, whether it is the external material world or the internal spiritual world. It is a vulgar truth to follow the secular world and say that the phenomenon is illusory. It is the true meaning to talk about the vacuum of reason when showing Buddhism. The two truths are interrelated, which is one of the basic principles of Mahayana Buddhism.