die there is nothing but the same eternal blackness and silence. Being alive is like having the brief light provided by a single candle burning in all that darkness. The light from that tiny candle-flame casts a shadow--and that shadow is us! The shadow walks around in the circle of light provided by the candle. We strut and fret. We think we are very important and that our desires, interests, and activities are of great significance. But we are only shadows which will disappear when that candle-flame goes out. Macbeth is wishing that his own personal candle-flame would blow out because he is tired of existence. He is utterly dejected. He sees how futile his own aspirations and expectations were, and by inference he sees the futility of everybody's aspirations and expectations. He sees not only the meaninglessness of life but its ridiculousness. Everybody who comes into existence for a brief moment in eternity is a fool because he thinks he is important and that what he does in his life must also be of great importance. Then he dies and loses everything he has acquired, and he is quickly and completely forgotten. The last two words of Macbeth's soliloquy summarize Shakespeare's pessimistic view of existence: "signifying nothing." Our existence ends up meaning nothing to ourselves and signifying nothing to anybody else. 

This quote is found in Act V, scene 5 of Macbeth.  

The entire quote, "All our yesterday 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," is Macbeth's comment on life and the "players" who walk the stage of life--a lovely metaphor.  He and his wife are two of those players.  Her life, ended much sooner than it should have, is the "brief candle"--the candle and her life have been extinguished.

He says that we all "strut and fret" upon the stage of life and then die--"are heard from no more."  Lady Macbeth's fretting and strutting are over...the curtain has closed, the candle is out.

Macbeth is busy when he hears the news of his wife's death, so he doesn't pay much attention to her death.  It can be viewed that he is cold and heartless at this point in the play, or that he is rationalizing his grief by putting it in context with the battle for which he is preparing at the time he receives the news of her untimely demise.  He does, however, realize the pointlessness of his ambition and how her candle (life) has been unnaturally shortened and in all probability, his candle will also soon be snuffed out.  Had he been patient and not "stirred" the pot to make his ambitions and goals a reality, they would have lived longer, more fulfilling lives.