We don't know how Keats personally saw the urn, but we know what he says in the poem about it. (They may be different.) In the poem about it, he indicates that art, and those thoughts, feelings, and actions portrayed in art, especially great art, are made immortal. Daily life is always stressful, in part because we know we're going to die, and will pass. Great art, though, lasts, and in this poem, it freezes those perfect moments forever, and the urn symbolizes that.
Critic Subrata Ray , thinks that Keats looks upon the Grecian Urn as the symbol of art and its immortality .The poem is dealt with the mutability of life and permanence of art .The idea was attempted by the poet in Nightingle Ode , and here , Keats executes his concept .
The bold lover and his mistress will ever feel the warmth of romance , and urge of union , remaining fresh and young .For they are captivated in the realm of art .
Again Time affects art tittle .But life falls victim to Time . .Here youth grows pale scepter thin and dies . The youth as engraved on the urn will will never grow old .
The Grecian Urn holds beauty of eternity , the human artist would pass away , but the urn will perpetuate .It would unlock its mystery to another artist saying the idea of truth in beauty .The Urn according to me symbioses the image of divine beauty .