Read the following excerpts:

Ozymandias
by Percy Bysshe Shelley (excerpt)

The hand that mocked them and the heart that fed;
And on the pedestal these words appear:
"My name is Ozymandias, king of kings:
Look on my works, ye Mighty, and despair!"
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.

Ode on a Grecian Urn
by John Keats (excerpt)

When old age shall this generation waste,
Thou shalt remain, in midst of other woe
Than ours, a friend to man, to whom thou sayst,
"Beauty is truth, truth beauty,"–that is all
Ye know on earth, and all ye need to know.

Which of these subjects do both excerpts address?