Note to Hamlet, 3.1.141: "O heavenly powers, restore him!"

Ophelia believes that Hamlet has gone mad before her eyes, but we know that there is another reason for Hamlet's wild anger. Ophelia, in saying that her father is "at home," has lied to Hamlet's face, and Hamlet must know this. Productions of Hamlet sometimes try to make the cause of Hamlet's reaction clear by, for instance, having Hamlet spot the toes of four shoes under the arras. I believe, however, that Hamlet's intuitive ability to detect lies and hypocrisy is sufficient explanation for his anger at the woman that he once thought he loved.