Riddle

“A, Beren, Beren! came a sound,
'almost too late have I thee found!
O Proud and fearless hand and heart,
not yet farewell, not yet we part!
Not thus do those of elven race
forsake the lover that they embrace.
A love is mine, as great a power
as thine, to shake the gate and tower
of death with challenge weak and frail
that yet endures, and will not fail”
― J.R.R. Tolkien: Beren and Luthien