While stage directions are unreliable in Shakespeare, the witches' lines reinforce the idea of Scene 1 taking place in a storm. It is an example of a pathetic fallacy that first introduces the relationship between the natural and the human worlds of the play. Here, the "hurly burly" of battle is reflected in a war of the natural elements, unnaturally so in that the battle is part of a civil war, a treachorous inssurrection against the divine right of King Duncan's rule. Such a setting is also appropriate for witches who want to upset the 'natural order' of the state by interfering in Macbeth's fate.