We gain our first insight into the character of Lady Macbeth in act 1 scene 5, where she is reading a letter from Macbeth (her patner in greatness), he speaks of his meeting with the "weird sisters" and what they have prophecised. Lady Macbeth upon reading this is excited by this great news and overcome with the belief that he will become the king - so her the queen - as is shown in the phrase "Glamis thou art, and Cawdor; and shalt be what thou art promised:".
Moreover, we then learn that she believes that Macbeth will be unable to do what is required to claim that title (kill king Duncan) as he is "too full o' the milk of human kindness".This is were we begin to see the first trace of the irony that runs throughout this play. As during the Elizabethan era - in which this play was written - women were regarded as the inferior sex, who were weak and feeble in comparison to men. However in this scene Lady Macbeth is portrayed as strong and she believes that her husband will not have the courage to do what she believes is necessary. She wishes that she could "pour my spirits in thine ear", showing how she believes that he does not have the determination, and strong will to overcome his good nature in order to gain what the witches predicted.
After the entrance and exit of a messanger, with the news that the King is on his way, Lady Macbeth reveals her almost psychotic personality as she calls to the evil sirits to come into her "Come, you spirits that tend on mortal thoughts, unsex me here,". The phrase "unsex me here" portrays once again how society in that era sees women as inferior;as she is begging the spirits to "unsex her" to free her from her female form and allow her to be male, so she could possess the physical strength to kill King Duncan.
We become aquainted with her plans to kill Duncan for sure, just before the "unsex me here" as she states "The fatal entrance of Duncan Under my battlements." This