One of the central images and symbols in Shakespeare's Macbeth that reveals the effect Macbeth's ambition has on Lady Macbeth is blood--specifically, King Duncan's blood.
When first the image and symbol of blood appears on Macbeth's hands, immediately after he assassinates Duncan (Act 2.2), Lady Macbeth dismisses it, saying that a little water will wash this deed (the assassination and all evidence of it including the blood) away.
But after Macbeth takes it upon himself to kill Banquo and Macduff's family, she suffers a breakdown, plagued by guilt. When she sleepwalks (Act 5.1), she wrings her hands, trying to get the blood off. A little water has not washed it away--nothing, it seems, can wash it away.
Macbeth's excessive ambition, and time, of course, lead Lady Macbeth to a breakdown and eventually to suicide.
In Act V, Scene 1, Shakespeare shows the downfall of Lady Macbeth and her repressed guilt beginning to surface in her hallucinations. The misdeeds her husband has committed turn out to be too difficult to deal with. The most striking image is the image of blood:
Who would have thought the old man
to have had so much blood in him...
Here's the smell of the blood still: all the
perfumes of Arabia will not sweeten this little
In this scene, Lady Macbeth believes that her hands are stained with blood and she is unable to remove the stains from her hands. The unwashed blood is a symbol of her guilty conscience. Lady Macbeth was the one who pressured her husband into following his ambitions and murdering king Duncan. At the beginning of the play, she seemed unperturbed by the fact that Macbeth would resort to illegal means to achieve his dream of becoming the king. It never occurred to her that she would be tormented by her guilt and eventually defeated by it.
The end of the play seems to suggest that Lady Macbeth is not so strong as she led us to believe. Macbeth's unbridled ambitions cause Lady Macbeth to become fragile, and the deeper Macbeth delves into the pursuit of his ambitions, the more vulnerable and helpless Lady Macbeth becomes. Everything she attempted to bury deep in her subconscious eventually comes backs to haunt her. Her only escape is death, to which she inevitably succumbs.