It's from Lord of the Rings -- an old song with lyrics written by Bilbo:
"Still round the corner there may wait
A new road or a secret gate,
And though we pass them by today,
Tomorrow we may come this way
And take the hidden paths that run
Towards the Moon or to the Sun.
Apple, thorn, and nut and sloe,
Let them go! Let them go! Sand and stone and pool and dell,
Fare you well! Fare you well!"
(excerpt from page 91)
In my opinion it's a clear implication that GR has bought the rights to Middle-Earth/Lord of the Rings RPG.
