Act IV of Macbeth
Act IV begins with the witches concocting a magical brew by stirring in disgusting ingredients to a boiling cauldron. When Macbeth demands that they answer his questions, the witches make apparitions appear out of the cauldron. ... The second tells Macbeth that he need not fear any man born of a woman. ... This apparition states that Macbeth wont be conquered till Birnam wood forest moves to the top of Dunsinaine Hill. Although the witches tell him to ask no more questions Macbeth still insist that they tell him more of the future.