The five main literary concepts in history include: reproducibility, expressiveness, practicality, objectivity and experience.
(1) Representation theory: It emphasizes the corresponding relationship between the world and works in literary elements, and holds that works are imitations or representations of the world.
(2) Expressionism: among the four elements of literature, the relationship between works and writers is emphasized, and works are considered as the natural expression of writers' feelings.
The basic tendency of expressionism is 1) literature is essentially the externalization of the inner world of poets and writers, the creation when emotions flow, and the product of subjective feelings and experiences.
(2) Expressionism also advocates taking external reality as the object.
(3) Poets can describe ordinary things, but they should present them in extraordinary colors.
To sum up, this problem should be performance theory.