An important theme in Macbeth is the relationship between gender and power, particularly Shakespeare's exploration of the values that make up the idea of manhood. Manhood, for most the characters in Macbeth, is tied to deals of strength, power, physical courage and force of well. Yet, it is rarely tied to the ideals of intelligence or moral fortitude. At several points in the play, the characters goads one another into action by questioning each other's manhood.
Lady Macbeth's character is a key to this theme of the relationship between manhood and power. At one point, she wishes that she is not a woman, so that she can kill the king. Her husband, Macbeth, also implies that she is a masculine soul inhabiting a female body. This seems too link masculinity to ambition and violence. Likewise, Lady Macbeth does not contradict Macbeth when he says that a woman like her should give birth only to boys. She mainly manipulates him by questioning his manhood.
In the same manner that Lady Macbeth goads her husband on to murder, Macbeth provokes the murders he hires to kill Banquo by questioning their manhood. Such acts show that both Macbeth and Lady Macbeth equate manhood with naked aggression, and whenever they converse about manhood, violence soon follows. Their understanding of manhood allows the political depicted in the play to descend into chaos.
At the same time, however, the audience cannot help noticing that woman are also sources of violence and evil. The witches' prophecies spark Macbeth's ambitions and then encourages his violent behaviour. Moreover, Lady Macbeth provides the brains and the will behind her husband's plotting.
Arguably, Macbeth traces the root of chaos and evil to women. While the male characters are just as violent and prone to evil as the woman, the aggression of the female characters is more striking because it goes against prevailing expectations of how women ought to behave. Lady Macbeth's behavior certainly shows that women can be as ambitious and cruel as men. Whether because of the constraints of her society or because she is not fearless enough to kill, Lady Macbeth relies on deception and manipulation rather than violence to achieve her end.
Ultimately, the play puts forth a revised and less destructive definition of manhood. In the scene where Macduff learns of the murders of his wife and child, Macbeth consoles him by encouraging him to take the news in "manly" fashion by seeking revenge upon Macbeth. Macduff shows the young heir apparently that he has a mistaken understanding of manhood. To Malcolm's suggestion, "Despite it like a man," Macduff replies, "I shall do so. But I must also feel it as a man." At the end of the play, Siward receivees news of his son's death rather complacently. Malcolm responds; "He's worth more sorrow / And that I'll spend for him." Malcolm's comment shows that he has learned the lesson Macduff gives him on the sentient nature of true manhood.
In conclusion, the idea of manhood seems to be one of the main theme in Macbeth. Through the characters of Macbeth, Lady Macbeth, Macduff and Malcolm, the audience is introduced to different definitions of manhood. With the contraction between Macbeth and Lady Macbeth, it is the cruel side of manhood which is revealed. Yet, the true view of manhood appears with Macduff and Malcolm.