Fear motivates many people to act upon matters, right or wrong. This emotion has been important in many events in both works of literature, and in the real world. It has forced military geniuses into retreat, and influenced them to plan another method of attack. Fear can be both a positive and a negative acting force in one's life, a quality that can motivate one to success as well as to downfall.
In the play Macbeth fear was a major motivating factor in character's actions. Macbeth was fearful of being caught and having to pay for the wrongs he had done this led to the murders that followed he killed King Duncan. Macbeth's actions were also partially driven by fear of the witches' last prophecy, about the line of kings spawning from Banquo. He was afraid this would come true attempted to prevent it from happening. Lady Macbeth was also plagued by fear as made apparent by the constant washing of her hands while sleepwalking and her speech during her troublesome sleep. Her fulfillment by the direst cruelty and pure evil has worn off, leaving her somewhat of a basket case, ridden by fear and guilt as a result of her actions.
After Macbeth kills Duncan, he is too scared to even carry the daggers back into the king's chamber. When the king's body is discovered, he kills the two guards that were in Duncan's room, and places the blame for the murderous deed upon them. His fear forces him to act this way in order to make him seem innocent. Macbeth's fear of being caught acts as an indicator of his guilt; however at first none of the other characters are able to realize this.
As Lady Macbeth becomes consumed by fear and guilt, she is slowly losing her sanity. This is a result of her not being able to handle what she has done to Duncan. In one scene, Lady Macbeth is trying to wash out what she sees as being blood on her hands, even though she is sleepwalking, though the doctor and woman in the room dare not blame her for anything, for fear of being accused