Two truths are told,
As happy prologues to the swelling act
Of the imperial theme.

– William Shakespeare

Macbeth, Act 1, Scene 3. Macbeth uses a metaphor to compare the Witches’ statements about his thaneships of Glamis and Cawdor to the prologue of a play. He speaks these lines on realizing that their prophecy about him being Thane of Cawdor has come true. The final act of the drama he sees as having a royal theme, when he becomes King of Scotland – the Witches’ second prophecy. The passage tells us of Macbeth’s ambition and desire for power and is foreshadowing of his later ruthless actions to acquire that power.