What type of figirative language is bright stars would you were steadfast as thou art?

The poem's main theme deals with the love and appreciation of things that are unchanging. This theme is brought up many times in the poem. For example, Keats uses a bright star and the earth to describe his innermost desires to be immortal, unchanged, and rejuvenated. He expresses deep feelings toward his lover, and if he had to live without her, he would welcome death.