In the final act of Macbeth, Lady Macbeth, who suffers from terrible guilt for having encourage Macbeth to slay Duncan, has lost her mind. However, when the doctor tells Macbeth that there is nothing that can be done by him for Lady Macbeth, Macbeth becomes enraged, insisting that the doctor find a cure while he continues to dress for battle, declaring, "I'll fight,till from my bones my flesh be hacked" (V, iv,31). The doctor leaves, fearing violence.
As the soldiers approach Dunsinane, Macbeth knows that he has no one that he can trust save the witches. He ponders how his life has become: He has had dinner with horrors, horrors that no longer frighten him. When news comes to him that Lady Macbeth has died, Macbeth has heard the cry of women and remarked that he has almost forgotten the taste of fear. Just then, Seyton enters to inform Macbeth is that the Queen is dead.
In his third and final soliloquy, Macbeth regrets the untimeliness of Lady Macbeth;s death: "She should have died hereafter" (V,v,17). His soliloquy reflects the insignificance of the individual life:
...all our yesterdays have lighted fools/The way to dusty death. Out, out, brief candle!/Life's but a walking shadow, a poor player/That struts and frets his hour upon the stage/And then is heard no more.
The day of someone's death is also the day of someone's birth, so the individual life is very insignificant. One's life is "a tale told by an idiot," a life that is meaningless to anyone else. One's life is very insignificant. "It is a tale/told by an idiot/Full of sound and fury/Signifying nothing."
Macbeth realizes that his desire for power has been meaningful for only a short time. With no one to trust other than his wife and the questionable witches, Macbeth senses the insignificance of his life as he awaits battle with Malcolm, Siward, and Macduff.
It is a tale/Told by an idiot, full of sound and fury,/Signifying nothing. (V,v,28-30)
Through violence, the meaning of life itself may be lost, Macbeth observes.