With Hamlet's attempts to appear insane by wandering and pacing through the halls, and by talking cryptically, he convinces many that his grief has driven him over the edge into insanity. Ophelia is among those who believes that Hamlet has lost his mind, which causes her great pain, "O, what a noble mind is here o"er-thrown! The courtier's soldier's, scholar's, eye, tongue, sword; Th" expectancy and rose of the fair state, The glass of fashion and the mould of form, Th" observ"d of all observers, quite, quite down!" (Hamlet, line 142-146, Act III*Scene I). Guildenstern and Rosencrantz both also believe that Hamlet has gone insane. They both are unaware of Hamlet's deception through most of the play. While many are convinced that Hamlet has gone completely insane, Claudius, Polonius, and Gertrude are very suspicious of Hamlet and are not entirely convinced. The king is very suspicious of Hamlet's insanity from the start. He refuses to allow Hamlet to return to his school, due to his suspicions, so he may keep tabs on his activities. Claudius learns through the play-in-the-play that Hamlet is aware of the truth of his father's death, which castes more doubt on Hamlet's insanity. One other example that demonstrates Claudius" knowledge that Hamlet is not insane is that he is threatened enough to order Hamlet's death.
As the play progresses, Polonius grows increasingly suspicious of Hamlet, and begins to believe that Hamlet is not as insane as many have come to believe. Even though Polonius does not understand the meanings of Hamlets comments and insults, he does come to understand some. After a conversation with Hamlet Polonius comments, "Though this be madness, yet there is method in"t." (Hamlet, Line 200, Act II*Scene II). As Polonius" suspicions grow of Hamlet's behavior, he decides to confirm his suspicions by hiding in Gertrude's room, so he could hear the conversations between Hamlet and his mother.
