Eternity

"The one remains; the many change and pass;
Heaven's light for ever shines; earth's shadows fly;
Life, like a dome of many coloured glass,
Stains the white radiance of eternity,
Until death tramples it to fragments."

On Fairy Stories

In this short dialogue between Aragorn and a rider of Rohan from Lord of the Rings is the essence of the argument Tolkien puts forward in his essay 'On Fairy Stories':

(Rider): 'Halflings! But they are only a little people in old songs and children's tales out of the North. Do we walk in legends or on the green earth in the daylight?'

'A man may do both,' said Aragorn. For not we but those who come after will make the legends of our time. The green earth say you? That is a mighty matter of legend, though you tread it under the light of day!'