Macbeth is the drama of man driven from crime to crime instigated by his wife, Lady Macbeth, and of its retribution by external forces.
Shakespeare's treatment of this central idea is manifested in the contrasted results of similar circumstances in two different natures - Macbeth and Lady Macbeth - one realizing itself in action and the other in thought.
For a villain to be a hero he must have sufficient greatness in his character to produce an impression of waste and there must be an internal struggle represented.
Thus, Macbeth first comes before us as a mighty warrior.
By personal valour he has saved his country from civil and alien foe.
This is the noble side of him.
Away from the battlefield he sinks to the level of quite common man.
Lady Macbeth's is both a subtler and nobler nature than his.
She has won her triumphs not in war but in the training of her intellect.
But she is a woman still I have given him suck and know How tender it is to love the babe that milks me.
Her immediate impulse to crime is ambition for her husband, and in the banqueting scene she stifles agonies of remorse to save him from blunders.
Thus the antithesis between the two is that between the practical life and the intellectual.
Macbeth is bold and resolute in the movement in action.
He can kill a king.
But when there is nothing to be done he is a prey to terrible imaginings.
Through the imagination he is liable to supernatural fears, and through it comes to him the intimations of conscience and honour.
The instant of murder is done, its futility is revealed to him Had I but died an hour before this chance I had lived a blessed time In all this Lady Macbeth is the exact reverse.
She has banished all superstitions from her soul.
She is strong enough to quell her husband's cowardly fears.
She can scheme and plot, but she cannot act.
She must leave the actual doing of the dastardly deed to her husband.
After the murder, Macbeth is stricken both with remorse and with fear of consequences.
In time, the fear of consequences drives him to new murders.
He becomes a craven and bloody tyrant.
Only in the last hour of battle does he recover his own brave spirit.
With Lady Macbeth the curse works itself out not in fear but remorse.
She has no hand in any murder but the first, but her sin is ever present to her.
Awake or dreaming she can think of nothing but the stain upon her hand and soul.
We witness the stiffed remorse and the agony of her natural feminine abhorrence of the sight and smell of blood in the sleep-walking scene: "Here's the smell of blood still; all the Perfumes of Arabia will not sweeten this Little hand.
Oh, oh, oh!" The awful agonized cry repeated thrice bespeaks of a heart "sorely charged".
She also recalls the murder of Banquo in which she sided with her husband, and to the senseless killing of Lady Macduff.
The details of Macbeth's crime jostle with those of her own.
She constantly longs for light and associates darkness with hell.
In spite of all her earlier brave words, her whispered horror, "Hell is murky", makes it clear that she was afraid of the world to come.
The "eternal feminine" in her nature rises in triumphant mutiny against her will.
Macbeth has murdered sleep - sleep having forsaken his eyelids - but Lady Macbeth's is a still direr curse to have sleep without its soothing powers.
A midnight wanderer she, with memory zigzagging through the horrors of the past and stimulating the senses into mock activity, the woman of steely will is reduced to robotic automaton helplessly blurting out her secrets to the doctor who pronounces her malady as beyond his skill, "More needs she the divine than the physician" At last she dies a voluntary and most wretched death - self inflicted - her collapse is complete.
Shakespeare here seems to be hinting a message that women, intelligent, independent, and ambitious, are far beyond man's capability of control, but the reverse - intelligent, independent, and sauve - she is placed between man and God.
She can make a man rise to the highest high of heights, and she can make him fall also to the lowest low of depths.
Macbeth is an 'abyss inian' example of the latter.