William Shakespeare's Macbeth proves to be a play which speaks to the quest for power. That said, Macbeth is not the only character who desires power. In act one, scene five, Lady Macbeth proves to be another character who desires the power a title will bring.
Perhaps the most prominent quote spoken by Lady Macbeth, which shows her desire for power, is found in lines 41-44:
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!
While power is not directly spoken of, one can readily see that Lady Macbeth desires power. Here, she is asking "spirits" to make her male, figuratively. She recognizes the fact that men are the ones who possess power. She, therefore, asks to be "unsexed" in order to possess the power to do what needs to be done. In this sense, "direst cruelty" parallels power for Lady Macbeth.
Compounding this idea, Lady Macbeth constantly questions Macbeth's maleness, stating that he is far "too full o’ the milk of human kindness" to do what must be done to take the throne from Duncan.
To find a quote that shows Lady Macbeth's ambition, take a look at Act I, Scene V. In this scene, Lady Macbeth has just read a letter from her husband in which she has learned of his new status as Thane of Cawdor and the prophecy that he will become king. Her reaction to this news demonstrates the scale of her inner ambition. She urges Macbeth to hurry home, for example, so that she can talk him out of whatever is preventing him from going after King Duncan's crown:
Hie thee hither,
That I may pour my spirits in thine ear
And chastise with the valor of my tongue
All that impedes thee from the golden round.
In addition, when Macbeth returns, she urges him to let her handle the preparations for Duncan's murder. It is clear from the following quote that she wants to do this because she knows that their future will be a bright one if Macbeth can become king. It is evident, therefore, that she, too, is seeking glory:
This night’s great business into my dispatch,
Which shall to all our nights and days to come
Give solely sovereign sway and masterdom.