In Shakespeare's "Hamlet", Hamlet's father appears as a ghost to those two soldiers in Act I, Scene 1. Upon hearing of his father's ghost and being left alone, Hamlet makes this short soliloquy: Foul deeds will rise, Though all the earth o'erwhelm them, to men's eyes. Meaning back in Hamlet's time, people believed people came back as avenging spirits once murdered. Earth meaning the soil on the grave, of course. Hamlet, fearing that the apparition may be a demon pretending to be his father, decides to put the ghost to the test by staging that play for Claudius'. Claudius' reaction of guilt and worry then leaves no doubt that Hamlet's father was murdered, just as he told Hamlet he was.
