I know this part of poetry (sound and sense) is difficult. Isn't it a bit like listening to classical music--you can be told about the terms and the effects, but then you need to listen/read more to cultivate your sensitivity to those effects.
You said, "We find it out that although the art is admirable, it can not give of bird or bush. As a result, the nature is more important than it." Is this a conclusion that the poet would like us to draw? Possibly, but then why does the speaker say that nature "rises up to it"?