George Gordon Noel Byron, Lord Byron (1788-1824), from "The Corsair", Canto I, xiv, 1-2

Deep in my soul that tender secret dwells, 
Lonely and lost to light for evermore, 
Save when to thine my heart responsive swells, 
Then trembles into silence as before.

There, in its centre, a sepulchral lamp 
Burns the slow flame, eternal - but unseen; 
Which not the darkness of Despair can damp, 
Though vain its ray as it had never been.