I am thy father's spirit,

Doom'd for a certain term to walk the night,

And for the day confin'd to fast in fires,

Till the foul crimes done in my days of nature

Are burnt and purg'd away. But that I am forbid

To tell the secrets of my prison-house,

I could a tale unfold, whose lightest word

Would harrow up thy soul, freeze thy young blood,

Make thy two eyes, like stars, start from their spheres,

Thy knotted and combined locks to part

And each particular hair to stand an end,

Like quills upon the fretful porpentine:

But this eternal blazon must not be

To ears of flesh and blood. List, list, O, list!

William Shakespeare (1564-1616): Hamlet. Act i. Sc. 5.