In Act I, scene 3 of Shakespeare's play, Macbeth wonders:"If good, why do I yield to that suggestionWhose horrid image doth unfix my hairAnd...

In Act I, scene 3 of Shakespeare's play, Macbeth wonders:

"If good, why do I yield to that suggestion
Whose horrid image doth unfix my hair
And make my seated heart knock at my ribs,
Against the use of nature?"
Does this imply that he has no control over his thoughts about committing regicide? Can it be that the witches are controlling him now? 
Expert Answers
rrteacher eNotes educator| Certified Educator

At this point in the play, Macbeth has just learned from Angus and Ross that he is to be named Thane of Cawdor. This was one of the witches' prophecies, and it has set Macbeth to thinking that the other prophecy--that he will become King--will also come true. Banquo, who also met the witches, is as amazed as his friend at the news, but he warns that the witches might be trying to lure Macbeth into a trap of sorts with their prophecies:

And oftentimes, to win us to our harm,
The instruments of darkness tell us truths,
Win us with honest trifles...

So Macbeth questions whether the "supernatural meeting" with the witches is good or bad. If it is bad, he asks, why does it seem to be true? If it is good, however, why does it start him thinking about the evil deeds that must be done in order to ultimately fulfill it? He is unsure what to make of these astonishing developments, but he concludes at the end that, "if chance will have me king, why chance may crown me without my stir." What the passage in the question suggests is that the witches' prophecy has caused him to think about committing horrible crimes. It seems not to enter his thoughts that he might ascend to the throne through natural causes. Macbeth is a frightfully ambitious man, and the witches have stoked these ambitions by hailing him as a future king. Whether they are controlling him is another matter. They (along with Lady Macbeth) certainly play on his ambitions and his willingness to trust them throughout the play, but ultimately Macbeth is the man who carries out the bloody deeds that bring about his rise and fall.