William Wordsworth's "Lines composed a few miles above Tintern Abbey" (1798) is one of the major early texts of the Romantic movement.
It is a textbook example of Wordsworth's definition of poetry as "the spontaneous overflow of powerful feelings from emotions recollected in tranquility."
This poem is almost guaranteed to appear on the GRE Literature exam. You should read the full text (Wikisource) of the poem at least twice before the exam.