Shakespeare's characters and themes in "Macbeth" are strongly developed right from the beginning. Shakespeare uses a variety of techniques to establish his themes and characters, via the dialogue and stage directions in his play. The introductory actions of the characters, along with the location and weather of the scene, work in conjunction with the language devices to quickly establish the key characters and themes.
A prominent theme of Macbeth is the supernatural. Shakespeare uses the witches as the centre of the supernatural and mystery in the play. Shakespeare establishes an atmosphere of evil connected to the witches by setting the scene during a storm to give a dark eerie mood. The isolated setting and anonymous witches further hints at a separate supernatural world. Shakespeare keeps the scene short for impact and dramatic effect. The witch's speech is trochaic and rhyming which contrasts with the blank verse the rest of the play is written in.
The trochaic rhythm is disturbing and pessimistic; it's an unnatural rhythm that sounds ritualistic like a chanting a spell, reinforcing supernatural theme. Their lines are very short for impact, and the speech seems to be split three ways as though the witches are finishing off each other's sentences,
'Second Witch: Upon the heath
Third Witch; There to meet with Macbeth'
This establishes the witches as a joint force which makes them seem more powerful. The witches call on animal helpers 'I come graymalkin...Paddock calls' use of inhuman helpers is further evidence of the supernatural and evil at work.
In the witches scene Shakespeare introduces the theme of nothing is as it seems. He uses antithesis in the witch's line, such as 'When the battle's lost and won', 'lost' and 'won' have conflicting meanings the same as 'lesser' and 'greater' in the line...