The theme of the passage relates to the theme from ode on Grecian urn by

The central theme of "Ode on a Grecian Urn" is the complex nature of art. The dramatic situation-the narrator's puzzling one-way exchange with the urn as he views the scenes painted upon it-is intended to provoke in the reader an awareness of the paradoxes inherent in all art, but especially visual art.

That art is an eternal and unchanging truth