Symbolism in “Ode on a Grecian Urn”

The symbolism in this poem starts with the title. An urn is used to store the ashes of a loved one whom was cremated. Setting aside theism, nothing does last forever. An urn itself may last a long time, but it will eventually fade. Ironically the urn houses something that has already surpassed its expiration date, a body. The urn seams to symbolize eternity. The figures on it have passed on but there visage lives on.

“Ah, happy, happy boughs! that cannot shed
Your leaves, nor ever bid the spring adieu;
And, happy melodist, unwearied,
For ever piping songs for ever new;”(Keats, l. 21-24)

Here the flora that is discussed is inferred as being deciduous, it will lose leaves come fall. The seasonal changes are of birth to death. On the urn however, the branches will never lose their leaves, they are immortal. Everything that is on the urn isn’t mortal anymore and will live on. The urn, however, will eventually disappear with time. It is ironic, but there is symbolism behind the text. While there are objects and being depicted on the urn as immortal, the urn’s time is finite. Does this mean that while everything is finite, something that outlasts is the thought, or truth, behind the urn.
The truth is the urn was thought of, carefully sculpted and plan. It will eventually be gone, but the fact that someone created it will never cease. “ `Beauty is truth, truth beauty,”—that is all / Ye known on earth, and all ye need to know.”(l. 49-50)
The only thing that seams to out last everything is truth, it is the one thing one the planet that will not die.