During Shakespeare's time, and throughout most of history, women were supposed to be submissive and obedient to their husbands. Women were supposed to be nurturing, peaceful, and at home attending to "womanly" duties. InMacbeth, the weird sisters have power of knowledge (of the future) and Lady Macbeth has ambition and courage--things that were more commonly associated in male characters and heroes. In a way, the women's positions of strength in the play emasculate Macbeth from the role of returning war hero and later as king. The reason Shakespeare does this is to add to the plot conflict, which is partly the conflict within Macbeth between doing right vs. doing wrong. What other power in the world usually brings men down? Shakespeare's answer might be "Women" when it comes to Macbeth and as seen in other plays likeThe Merry Wives of Windsor. Also, when a woman lacks faith in her man, it seems like the most natural thing for her to do is to steer him in the directions that she sees fit is best for the both of them. Hence, in I.v., Lady Macbeth says, "Glamis thou art, and Cawdor, and shalt be/ What thou art promised. Yet do I fear thy nature;/ It is too full o'the milk of human kindness/ . . . I may pour my spirits in thine ear,/ And chastise with the valor of my tongue" (I.v. 13-15, 23-24). From these lines we see that Lady Macbeth plans to take control of Macbeth's situation rather than worrying about her role as potential queen. She also isn't standing up for honesty and honor, which would be a "womanly" thing to do when compared to what Christian women "should" do or be. Without the inverted gender roles, the plot of Macbeth would not be as thick as it is, nor would it be the work of art that it is.