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In act 4 sc.1, three apparitions conjured up by the witches prophesy all about Macbeth's ruin, though in an ambiguous riddle-like language. Macbeth insists on knowing more, especially about the prospect of kingship as promised to Banquo's issue. The witches then present a show for Macbeth :
" A show of eight Kings, the last with a glass in his hand; Banquo's Ghost following".
All the eight kings look like Banquo. The crown that the first wears burns Macbeth's eye-balls. The second and the third also wear the same dazzling crown. Macbeth, disturbed at the sight, curses the witches as 'filthy hags'. As the procession of kings goes on, Macbeth is outraged to believe that Banquo's look-alikes would be marching on and on till the very end of the world. Macbeth finds that the eighth in the line holds a mirror which shows many more kings to follow. Some of these eight kings carry with them 'two-fold balls' and 'treble sceptres'; the first signifies the two crowns of England and Scotland united under James I, while the second suggests the three kingdoms of England, Scotland and Ireland. Banquo's 'blood-bolter'd' spectre smiles sarcastically at Macbeth.