In Act 3 Scene 1, Macbeth's soliloquy shows his fear that the second half of the witches' prophecy will come true and that Banquo's sons will eventually become the line of kings in Scotland. In the soliloquy, Shakespeare uses several metaphors to describe the situation. For example, Macbeth complains of the "barren sceptre" that he holds to suggest that he will have no sons to whom he might pass the throne. Also, Shakespeare makes an allusion to one of his other plays, Julius Caesar to compare Macbeth's dilemma to one with which his audience is already familiar. This soliloquy is important because it details the complex nature of Macbeth's inner conflict and provides a reason for Macbeth's next plan--the murder of Banquo.