What is the significance of the conversation between Lady Macduff and her son?
The conversation between Lady Macduff and her son is significant, as it shows the intimate link in the play between the political and the personal. It's all too easy for us to become so immersed in the high politics of Macbeth that we overlook the consequences of all this plotting and scheming upon family and individuals.
We might expect Lady Macduff to understand the reasons behind the sudden absence of her husband. She is someone, after all, who must have some idea of what political life in Scotland involves; she certainly isn't naive. But as well as being a member of the nobility, she's also a woman and a mother. It's in those capacities that she feels betrayed and abandoned. Her son, though still only a young boy, also feels much the same way.
There is an interesting tension in this scene between the perspective of Lady Macduff and her son and that of Ross, who attempts to justify Macduff's desertion on the basis of reasons of state. It's Ross who tries to get Lady Macduff to see the bigger picture, as it were, to get her to understand that there are sound political reasons for Macduff's sudden departure. In other words, he's separating the personal from the political.
But Lady Macduff isn't having any of it. As far as she's concerned, her husband is dead to her; and there's nothing in this scene to challenge her judgement on the matter. Ross's defense of Macduff certainly doesn't. His apology for his cousin's actions is brief and largely unconvincing, making us sympathize all the more with an innocent wife and child now cruelly abandoned and left to meet their fates.
This short scene from Act 4, sc. 2, shows how Lady Macduff feels about her husband's absence and shows the general current mood of Scotland. Lady Macduff is angry that her husband has left them in Scotland to go to England. She implies that things are so bad in Scotland that she feels vulnerable and unsafe with him gone (she obviously has good intuition). She tells her son that her husband is dead, which, in a way, he is to her right now. Her son knows better and realizes that his mother is simply angry with her husband and is speaking metaphorically. Ross, her cousin, tries to soothe her, but she says if her husband loved her and his family, he would not leave them alone. Later, in the next scene, when Malcolm tests Macduff's loyalty to Scotland, that loyalty is clearer to the audience who has seen how Macduff left his family in harm's way to help his country.