SARAH:  At the end of Act I scene 5, just after the ghost has exited the stage, Hamlet tells his friends that no matter how strangely he may behave back at the court, they shouldn’t act as if they know anything about it.  Hamlet explains that he may find it necessary to put on an “antic disposition”, that is to feign madness, to act like he’s gone insane. The word antic means absurd, grotesque or bizarre.

RALPH:  That’s right Sarah, Hamlet is employing a traditional strategy familiar from legend and literature — an opponent to a powerful villainous ruler feigns madness in order to deflect suspicion while he waits for an opportunity to act against the tyrant. The most famous character to employ this tactic was Lucius Junius Brutus of ancient Rome.

SARAH:  That’s the Brutus who assassinated Julius Caesar?

RALPH:  [patronizing chuckle] No, Sarah, it’s a different Brutus, one of his ancestors. Centuries before Julius Caesar, when Rome was still ruled by the Tarquin clan, one of the king's sons raped Brutus' cousin, Lucretia, who then killed herself out of shame. The young Brutus vowed revenge, but in order to avoid suspicion by the king, he pretended to be a harmless fool until the time was right. Eventually he organized a rebellion, overthrew the Tarquins, and founded the first Roman republic.

SARAH:  This legend was well known in Shakespeare’s time since it was told as a morality story, and it was the subject of a long epic poem that Shakespeare wrote:  The Rape of Lucrece. This strategy was also used as a plot device in other revenge plays.

RALPH:  Shakespeare’s audience would have likely been familiar with Hamlet’s strategy, and ready to enjoy the confusion caused by Hamlet’s behavior.