The reason for this is because Banquo was present when three witches predicted that Macbeth would become king and found it doubtful that the king had been murdered. Macbeth, in response, attempts to kill Banquo and his son Fleance, but only succeeds in killing Banquo. Macbeth seems to have lost his fear at this point and continues to slaughter anyone who dares to oppose him, regardless of whether they are friend or foe. He has also descended into a deeper point of madness, as shown in scene iv of Act III, when Macbeth sees Banquo's ghost in his dining room which no one but him is able to see. The other thanes are present at this event and have the psychological change in Macbeth, and are able to see that he is not