List Huang Tingjian's main views on poetry.

Huang Tingjian was a famous writer and poet in Song Dynasty, and his poetic theory had far-reaching influence. The following are his main views on poetry:

1. The theory of "turning iron into gold": This is a theory of poetry creation advocated by Huang Tingjian, which emphasizes that poetry needs to be repeatedly pondered and mended, and finally achieves perfect artistic effect. This view shows that a good poem needs to be tried and improved many times and constantly strives for perfection before it can reach a perfect state.

2. Poetry is based on "Tao": Huang Tingjian believes that poetry is an art form that expresses the high achievement and universal perfection of human nature by expressing the poet's thoughts and feelings, moral cultivation and life concept. Therefore, an excellent poem must have profound ideological connotation and philosophical significance.

3. Pay attention to expressing emotions: Huang Tingjian believes that poetry should pay attention to expressing the poet's emotions. Emotion is the soul of poetry, and only poetry with true emotions can touch people's hearts.

4. The theory of "replacing bones with fetuses": This is another important viewpoint in Huang Tingjian's poems. He believes that poetry should absorb nutrition from other people's works, just like "robbing a fetus to replace a bone". Only through its own processing and revision can it write better works.

These are Huang Tingjian's main views on poetry. His views had a far-reaching impact on later poetry creation and theory.