Macbeth: Is this a dagger which I see before me,
The handle toward my hand? Come, let me clutch thee:
I have thee not, and yet I see thee still.
Art thou not, fatal vision, sensible
To feeling as to sight? Or art thou but
A dagger of the mind, a false creation,
Proceeding from the heat-oppressèd brain?
I see thee yet, in form as palpable
As this which now I draw...

Macbeth - William Shakespeare - Macbeth Monologue Act 2