Answer :
In the poem "Solitary Reaper," the line "Long after it was heard no more" is most thematically similar to the theme of eternal art in "Ode on a Grecian Urn."
Here's why:
1. In "Ode on a Grecian Urn," the theme of eternal art is highlighted through the description of the scenes depicted on the urn that will last forever, frozen in time.
2. Similarly, in "Solitary Reaper," the line "Long after it was heard no more" implies that the impact of the maiden's song will endure even after the immediate moment has passed.
3. Both lines suggest a sense of permanence and timelessness, emphasizing the lasting power of art and beauty beyond the immediate present.
By drawing parallels between these lines from the two poems, we can see how both convey the idea of art transcending time and leaving a lasting impression on those who experience it.