What is the effect of Banquo's ghost on Macbeth?
Macbeth is thrown completely for a loop at the appearance of Banquo's ghost. Only he can see the ghost, and the entire time he is babbling, Lady Macbeth tells him to be a man thinking that Macbeth is still blubbering about Duncan's murder. He becomes unhinged because every time he toasts Banquo or mentions his name, the ghost reappears and takes HIS seat...the seat that Fleance and Fleance's sons are prophesied by the witches to take at some point in the future.
Everyone leaves thinking that Macbeth is touched in the head, and now new suspicion of foul play is cast on him.