Why are the witches in the play?

The inclusion of the witches at the beginning, middle and end of the play, provides a constant reminder to the audience of the supernatural elements that are present throughout the play. In addition as conventionally witches are associated with teh dark arts and being evil they add to the Gothic nature of the play. The sing-song manner in which the text is presented is hypnotic perhaps suggetsing that they hold a certain influence over Macbeth. The witches personify corruption aoing against nature and being women with beards, so when Macbeth asks for their advice in act VI this shows clearly to the audience/reader how he is progressively siding with evil. Their inclusion also questions Macbeth's motivation - is he simply a cold herated murderer, or is he being toyed with by greater forces? They are also included for dramatic purposes - their presence contrasts the generall naturalism of dialogue between charcters, as their speech is rythmical often rhyming and in the stage directions it describes how they 'dance'. There inclusion creates variety and is an example of surrealism which ensures teh audience's/readers interest is maintained.