Short Answer 
John Keats explores the theme of eternal art in his poem ‘Grecian Urn,’ emphasizing its ability to immortalize moments, while in ‘Seeing Elgin Marbles,’ he acknowledges life’s transience and the inevitable fading of all art. This contrast highlights the duality of beauty’s permanence versus life’s impermanence, reflecting Keats’ nuanced understanding of art’s place in the passage of time.
Step 1: Explore Themes of Eternal Art
In the poem ‘Grecian Urn’, John Keats presents the concept of eternal art, emphasizing the lasting power of the vase. He uses the word “forever” multiple times to highlight the idea that the image captured by the urn transcends time. This repetition underlines the notion that art immortalizes moments and emotions, making them eternal.
Step 2: Acknowledge Life’s Transience
Conversely, in ‘Seeing Elgin Marbles’, Keats confronts the reality of impermanence. He reflects on the fleeting nature of life and how everything, including art, will eventually fade away. Through this poem, he expresses a profound sense of loss, as he recognizes that even the grandeur of the Elgin Marbles will not escape the passage of time.
Step 3: Synthesize the Contrasting Ideas
Ultimately, Keats juxtaposes the enduring beauty of art with the harsh truth of life’s temporality. While ‘Grecian Urn’ celebrates art’s ability to preserve beauty forever, ‘Seeing Elgin Marbles’ reminds us that all things must eventually fade. This duality reveals Keats’ understanding that while art can encapsulate moments, it too is subject to the ravages of time.