Torchwood, Series 1

[talking about his former love, Estelle's, visions of fairies]

Jack:
She calls them fairies. I don't.

Gwen:
What do you call them?

Jack:
Never really had a proper name.

Gwen:
Why not?

Jack:
Something from the dawn of time, how could you possibly put a name to that?

Gwen:
Are we talking alien?

Jack:
Worse.

Gwen:
How come?

Jack:
Because they're part of us. Part of our world, yet we know nothing about them. So we pretend to know what they look like. We see them as happy, we imagine they have tiny little wings and are bathed in moonlight.

Gwen:
But they're not?

Jack:
No. Think dangerous. Think something you can only half-see, like a glimpse, like something out of the corner of your eye. With a touch of myth, a touch of the spirit world, a touch of reality all jumbled together, old moments and memories that are frozen in amongst it. Like debris, spinning around a ring planet, tossing, turning, whirling... backwards and forwards through time.