I wonder if there are any other two lines that are debated so much. The closing couplet to the poem is really profound. There will be no easy answers here and I strongly advise you to take what you find here, what you find in your class discussions/ notes, your instructor's analysis, and, most importantly, your own perceptions and merge them together in understanding the last two lines. I think that the context of the poem of Keats staring at this urn and the beauty within it is important. The urn is the launching pad for the philosophical ideas and the inquiry that Keats explores in the poem. The challenge here though is that Keats struggles to make the leap between what is happening in the urn and the world outside of it. Art has the advantage of being cloistered in one moment in frozen time. The beauty of the urn is suspended because it is within art. As an artist, Keats was driven with the idea of how can art's perfection be something within the grasp of the real world. Probably more than any other Romantic thinker, Keats was animated with a sense of this notion of artistic and aesthetic perfection in his work. How does he, as an artist, create a realm that transcends frozen conditions and brings out the essence of truth and beauty? How does one move from mere abstraction to actual replication of such elements? His closing lines might be a way for him to attempt to make peace with the fact that elements of truth and beauty might lie beyond his grasp, beyond anyone's, and simply exist as a realm for us to wish to enter, where "angels dare to tread." It is almost as if the last lines create a sweet pain of consciousness where we know that we will never be able to create such elements in our art, but rather to simply behold them and bask in their presence is enough. When Keats sees the beauty and truth of the urn, it fills him with enough satisfaction to be able to appreciate and express that he can feel such an experience. This subjective conception of supposedly objective ideals is consistent with Romantic tendencies. At the same time, the closing lines help to bring out the "negative capability" that is such a part of Keats' work and Romanticism in its response to the Enlightenment period's affirmation of scientific inquiry. The idea that there are realms where we, as human beings, must be content with the unknown is something that Romantics, and especially Keats, advocated, and the closing couplet to the poem might be a statement in this light, as well.