Hamlet Act 1 Scene 5 notes

Ghost is in this state of purgatory and confirms that he is Hamlets father. Ghost states "Revenge his foul and most unnatural murder." Ghost also reveals that it was Claudius that killed him with poison in order to take the throne and also seduced the queen prior to hamlets death. Ghost wants hamlet to kill his uncle, but leave his mom to god and her own guilt. 

Hamlet suspected Claudius and as soon as his fathers ghost confirms that Claudius killed him, hamlet knows that in turn hamlet must kill Claudius. Every day hamlet doesn't kill Claudius he looks down on himself more and more.

Hamlet ducks away from anybody's question regarding anything that the ghost said to him. 

"There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."

"The time is out of joint: O cursed spite, That ever I was born to set it right!"