Lines 6-7 contributes to the development of a theme in the poem because it shows that beauty doesn't last forever it will fade away. "So Eden sank to grief." It says that Eden was paradise and it sank away. "So Dawn goes down to day." This shows that Dawn also sank away, which shows that beauty goes away, but never lasts.
I am pretty sure it would be massive because it is an English question. If you are doing a multiple choice question you should see which one fits the best. If could also be positive impact.
