After seeing the ghost of his father, Hamlet promises to avenge his death and decides that faking his madness will provide him with the means to prove Claudius' guilt. Following his first meeting with his father’s ghost, Hamlet is eagerly speaking with Marcellus and Horatio and tells them: “but come / Here, as before, never, so help you mercy / How strange or odd soe'er I bear myself- / As I perchance hereafter shall think meet / To put an antic disposition on- / That you, at such times seeing me, never shall, / With arms encumbered thus, or this headshake, / Or by pronouncing some doubtful phrase /.... That you know aught of me - this do swear, / So grace and mercy at your most need help you.” (Act 1, Scene 5, Lines 177-189). Hamlet explains in this passage that if he is appearing to be acting mad, or putting on an "antic disposition," they should not be worried or act as if they know some secret about him. His plan to fake madness provides him with the means which to act and speak in ways which would under normal conditions would not be acceptable. Thanks to his plan of faking his madness he is able to prove Claudius'