What separates Hamlet from other revenge plays (and maybe from every play written before it) is that the action we expect to see, particularly from Hamlet himself, is continually postponed while Hamlet tries to obtain more certain knowledge about what he is doing. This play poses many questions that other plays would simply take for granted. Can we have certain knowledge about ghosts? Is the ghost what it appears to be, or is it really a misleading fiend? Does the ghost have reliable knowledge about its own death, or is the ghost itself deluded? Moving to more earthly matters: How can we know for certain the facts about a crime that has no witnesses? Can Hamlet know the state of Claudius’s soul by watching his behavior? If so, can he know the facts of what Claudius did by observing the state of his soul? Can Claudius (or the audience) know the state of Hamlet’s mind by observing his behavior and listening to his speech? Can we know whether our actions will have the consequences we want them to have? Can we know anything about the afterlife? Many people have seen Hamlet as a play about indecisiveness, and thus about Hamlet’s failure to act appropriately. It might be more interesting to consider that the play shows us how many uncertainties our lives are built upon, how many unknown quantities are taken for granted when people act or when they evaluate one another’s actions.