Hmm.... this is a tough question. I'd have to say the poetry/songs that Tolkien created throughout his pieces. People often skip over the fact that he was an objectively talented poet even outside of the fantasy context.
"O! Wanderers in the shadowed land
Despair not! For though dark they stand,
All woods there be must end at last,
And see the open sun go past:
The setting sun, the rising sun,
The day's end, or the day begun.
For east or west all woods must fail."