"I essentially am not in madness, But mad in craft." (III. iv. 187-8.)
Hamlet doesn't really like his mother in the beginning because he feels she was to quick to jump into bed with Claudius. Hamlet loves his mother and doesn't want to kill her but he tries to convince her that she is with the person that murdered her past husband. In the scene after the play Hamlet goes to confront his mother about what she is doing. They get into a heated argument over his actions and her actions. Hamlet ends up shooting Polonius but he thinks its Claudius spying and listening to their conversation. During this scene the the Hamlets father appears as a ghost and Hamlet goes over and talks to it. At the same time Hamlets mother says he's crazy because she cannot see the ghost he is supposedly talking to. This brings up the statement of how Hamlet is actually insane as his mother cannot see the ghost he sees. But is the ghost even there to begin with. These are the situations that border the line of Hamlets state of mind.