What kind of thoughts and feelings does this poem express?

The whole poem expresses the poet's infinite praise for the tenacious vitality of a grass and a tree. Trees are lonely and tenacious, and have a kind of vitality that can't be exerted.

In the invisible depths, they cling to their roots.

This sentence reflects the tenacity of the tree.

The poet praised the indomitable spirit of the Chinese nation through the big tree.

tree

A tree, a tree

Stand apart from each other

Wind and air

Tell them the distance

But under the cover of soil,

Their roots have been elongated.

In the unseen depths

They tangled their roots together.

Trees are just a concrete thing in nature. The poet entrusts things to the tree, praising a spirit of unity and struggle that is independent, progressive and rooted. The high integration of image and thinking is the common feature of all successful literary works.

"Poetry should think in images", and the poet created the artistic conception with the help of the image of trees as a natural object. Through this perceptual image, the rational understanding of reality has become the concept in the poem. A tree, a tree/independent of each other/wind and air/telling their distance. This is an independent tree. Then the poet wrote with the image of "root": "In the invisible depths/they entangled the roots". These trees, which are connected with each other underground, form an ideological understanding for readers: trees are both independent individuals and United whole. Write God in form, which is the essential feature and spiritual character of the object. Of course, the emotion in the poem is not abstract, but dissolved in the image of the poem.