The opening scene of Macbeth is short, and rather ambiguous. It seems that Shakespeare is primarily using it to set a mood for the play, but audiences can also detect a few hints as to what is to come. There is thunder and lightning, and the scene is described as "a desert place." The witches appear, and make it known that they will meet again with Macbeth after a battle. Shakespeare uses the juxtaposition of opposites to suggest that all will not be as it appears in the play, beginning with the witches' agreement that they will meet "when the battle's lost and won," and ending ominously by saying "Fair is foul, foul is fair." So in this short scene, Shakespeare both foreshadows the evil that is to come in the play while simultaneously raising questions about the relationship between the supernatural (in the form of the witches) and human agency.