There are three very notable hallucinations that Macbeth experiences. One is the dagger that he sees floating before him just before he is about to murder Duncan. Just after he kills the king, he fancies he hears voices calling out that 'Macbeth does murder sleep!' (2.2. 33). Later, once he has become king, and arranged for the murder of Banquo, he sees Banquo's ghost. These visions and hallucinations all testify to the fact that he is slowly becoming unhinged. To begin with, he did not really have it in him to murder; he has to force himself to kill Duncan, and his hallucinations just before and after committing this crime demonstrate how disturbed he is over it. Once he begins his path of crime, however, he becomes ever more reckless, killing more and more, but this is essentially out of a sense of increasing despair - he feels he is beyond all salvation and this drives him slowly insane. This also happens to Lady Macbeth: her overriding sense of guilt and remorse manifests itself in her sleepwalking where she obsessively tries to scrub out bloodstains.