Given that one of the central themes to William Shakespeare's tragic play Macbeth is the corrupting power of ambition, Lady Macbeth's character can be found as guilty of unchecked ambition as her husband, Macbeth.
From the instant that Lady Macbeth found out about the witches' prophecy regarding Macbeth's rise to the crown, her ambitions to be the wife of a king soared. Already planning the murder of Duncan, Lady Macbeth believed that her husband was not man enough to do what needed to be done.
Yet do I fear thy nature;
It is too full o' the milk of human kindness
To catch the nearest way. Thou wouldst be great;
Art not without ambition, but without
The illness should attend it.
Lady Macbeth simply understands what it takes to be a king, as well as take a throne. Therefore, based upon her distrust of Macbeth's "manliness," Lady Macbeth asks the "spirits" to help her to do what needs to be done.
Come, you spirits
That tend on mortal thoughts, unsex me here,
And fill me from the crown to the toe top-full
Of direst cruelty! make thick my blood;
Stop up the access and passage to remorse,
That no compunctious visitings of nature
Shake my fell purpose, nor keep peace between
The effect and it!
Lady Macbeth knows that men are the ones who are known to be, and supposed to be, hard enough to fight and take what they want. Women, on the other hand, are simply thought to be too weak. Knowing this, Lady Macbeth wants to be a man so that she can take the crown (to insure that it happens). Therefore, Lady Macbeth's actions show her character to be one whose ambition is far greater than it should be. It has gone unchecked.