How does Lady Macbeth respond to Macbeth's state of mind in Act 3 Scene 4?
Macbeth's state of mind is revealed by the fact that he continuously sees the newly-murdered Banquo's ghost at the banquet he is hosting (which Banquo was riding to attend when Macbeth had him murdered). He begins speaking to the apparition in front of his thanes, which concerns Lady Macbeth. She assures him that the vision is, like the one of the dagger he saw before killing Duncan, nothing but fear acting on his brain, and she chastises him for feeling this way. He is, according to Lady Macbeth, "quite unmann'd" by the vision. It becomes clear that Macbeth is consumed by guilt for his actions, and Lady Macbeth, in addition to trying to fortify his spirit (as she has done since Act I) also tries to downplay his visions and keep up appearances with his dinner guests. Eventually she dismisses them, saying her husband is overcome by some sort of malady that causes him to see things. This scene is a sort of turning point in Macbeth. After the banquet, it will be Lady Macbeth that is overcome with visions, a symptom of her own guilt, and her husband that has become a murderous, pitiless monster. But in this scene, she responds to Macbeth's guilt as she has throughout--by attempting to strengthen him by challenging his masculinity.
In the very beginning of the scene Macbeth and Lady Macbeth are both attempting to portray a united sense of calm and ease in their recently acquired positions of power. When they enter the banquet Macbeth says to the guests: