He included them because they are in his source. Shakespeare took the play Macbeth from a book called Holinshed's Chronicles, a history of the various kingdoms of Britain. In telling the story of Macbeth, Holinshed says this:
"It fortuned that as Makbeth and Banquho had iourneyed towards Fores where the king then laie, they went sporting by the waie without other company, save onlie themselves, passing through the woods and fields, when suddenlie, in the middell of a laund, they met them three women in strange and wild apparell, resembling creatures of elder world, whom when they attentivelie beheld, wondering much at the sight, the first of them spake and said: 'All haile Makbeth, Thane of Glamis' (for he had latelie entered into that dignity and office by the death of his father Sinell). The second of them said 'Haile Makbeth Thane of Cawder'. But the third said 'All haile Makbeth that hereafter shall be king of Scotland.'
"Then Banquho; 'What manner of women (saith he) are you, that seem so little favourable unto me, whereas to my fellow here, besides high offices, ye assigne also the kingdome, appointing forth nothing for me at all.' 'Yes (saith the first of them) we promise mise greater benefits unto thee, than unto him, for he shall reigne in deed, but with an unluckie end, neither shall he leave any issue behind him to succeed in his place, where contrarilie thou shalt not reigne at all, but of thee shall be borne that shall governe the Scottish kingdom by long order of continuall descent.' Herewith the foresaid women vanished immediatelie out of their sight."
As you can see, Shakespeare followed Holinshed quite closely.
The witches
They thought witches were real in his time, so they were a natural predictor for telling the future in his plays.
That would be (*whispers*) Macbeth.
Strange and unnatural events
There were a lot of people who really believed in witches. However the witches in Macbeth are not to be taken seriously: they have silly songs and dances and speak in silly rhyming couplets. But they were inserted (probably by Thomas Middleton who wrote one of the songs) because that portrayal of witches was extremely popular and the audience wanted more.
The witches
They thought witches were real in his time, so they were a natural predictor for telling the future in his plays.
Audiences during Shakespeare's time considered witches and curses to be real and much scarier than todays audiences would.
That would be (*whispers*) Macbeth.
Well, many people have probably been told they wouldn't be king by "witches," but the most famous example would probably be Banquo in Shakespeare's "Macbeth" who was told that his children would be kings though he would not, by the three witches who prophesy throughout the play.
Strange and unnatural events
Strange or unnatural events
they believed in witches and ghosts. in Shakespeare's play Macbeth they would have really believed that banqos ghost had come back to haunt Macbeth they had several superstitions to do with ghosts.
Macbeth was written and performed for King James. Shakespeare wanted to please the king, so he wrote a fairly short play (James liked short plays). King James himself had written a book on witches and how to detect them. For this, Shakespeare decided to add a supernatural twist to his play, as to please the king. Basically the King wrote a book about witches so Shakespeare thought putting witches in his play would please the king. Source: http://home.flash.net/~manniac/macb.htm
There were a lot of people who really believed in witches. However the witches in Macbeth are not to be taken seriously: they have silly songs and dances and speak in silly rhyming couplets. But they were inserted (probably by Thomas Middleton who wrote one of the songs) because that portrayal of witches was extremely popular and the audience wanted more.
According to the witches, Banquo's descendants would rule. Allegedly King James I of England was one of his descendants because he ruled in the time of Shakespeare and the author wished to be in good graces with the King.
Duncan is a Scottish name. The name was based on a clan name and was the name of a Scottish Saint. I think the most famous Duncan would be the one who was in Shakespeare's MacBeth