The moment Macbeth started feeling guilt over the death of the king, his guilt multiplied tenfold and his mental deterioration escalated. guilt drives him to think that Banquo

saw him murder Duncan though it was not the case. ... Macbeth's mental deterioration is evident from the beginning of the play.

How does Macbeth mental state change?

Macbeth gradually becomes a tyrant as his mental state declines. He becomes a bloodthirsty, unsympathetic ruler, who is overconfident in his abilities to retain his title as king. By the end of the play, Macbeth is an isolated, defeated tyrant, who cannot defend his throne.

How does Macbeth lose his mind?

Mental Decline In Macbeth

Finally, Macbeth 's greediness and committing murder drives him to experience guilt and causes his mental decline. To begin, when he decides to kill Duncan, Macbeth hallucinates and questions “is this a dagger I see before me” (Shakespeare II.