From “Macbeth,” Act II. Sc. 1.
  
  [MACBETH, before the murder of Duncan, meditating alone, sees the image of a dagger in the air, and thus soliloquizes:]

  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
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