Act Four Scene One: MACBETH: "Then live, Macduff. What need I fear of thee?/But yet I'll make assurance double sure,/And take a bond of fate: thou shalt not live."
Interpretation: Macbeth is trying to maintain control over his own life. He believes that by killing Macduff, he is guiding his own fate.
Analysis: Macbeth's nervousness and fragility is evident here - rather than the brave warrior from the beginning of the play, now he is desperate to be "sure" and needs "assurance". It also shows the conflict in his mind- he starts by suggesting that Macduff can "live", but follows this with a question, and then a complete contradiction, saying "thou shalt not live". We also see Macbeth's lack of actual power as he needs to "take a bond of fate", relying on fate to assist him.