Celtic Twilight is a term for writing, especially Irish poetry and prose, that draws on folklore, legends, dreams, ghosts, and mystical or spiritual moods. It is strongly associated with W. B. Yeats and the Irish Literary Revival, where everyday life is often mixed with older myths and a sense of the enchanted past. The phrase can also refer more specifically to Yeats's early collection The Celtic Twilight.
Example
The moor went silent at dusk;
a woman in a faded shawl
said the lake kept the names
of those who had listened too long
to the fairies in the reeds.