John Keats and Percy Bysshe Shelley both use a material object as a metaphor in their poems to demonstrate the ability or inability of anything to endure temporal change. While Keats" "Ode on a Grecian Urn" is a meditation of the timelessness of an Urn, Shelley's uses a statue to represent the failure of anything to endure over time in his poem "Ozymandias." Keats" Grecian urn, passed down through countless centuries to the time of the speaker's viewing, exists outside of time in the human sense; it does not age nor die. However, for Shelley, just as the statue of Ozymandias is broken and changed from its intended form, so too does the meanings of words change. The statue of Ozymandias in Shelley's poem represents the instability and destruction of all things over time. Whereas, the Urn in Keats poem represents the preservation of moments and the ability of a specific art form to transcend time. Keats intends to question the desirability of timelessness because to transcend time one must sacrifice sensual pleasures. .
Although the urn depicts history through its pictures, it remains unchanged over time. This phenomenon is possible because unlike other art forms, the urn is not bound by time. Music and poetry are both dependent on time to interpret and understand their forms. However, one can take in the form of the sculpture in a single instant. This is because the urn is spatial rather than temporal. The silence of the urn enables its sense of timelessness. Although "heard melodies are sweet . . . those unheard are sweeter" (l. 11, 12). This is because when melodies are not bound by time but rather are in one's imagination they can last forever. However, the silence that emphasizes the timelessness of the urn also implies the cruelty of the urn. For in its sense of timelessness, the urn teases man with the idea of eternal beauty, which may not exist. Keats is uncertain of the possibility and the desirability of eternal and immortal beauty.