"I am thy father' s spirit, doomed for a certain term to walk the night and for the day confined to fast in fires." (1.5.14-6)
"Revenge his foul and unnatural murder." (1.5. 31)
Claudius betrays King Hamlet.
"Tis given out that, sleeping in my orchard, a serpent stung me." (1.5.42-43) "But know, thou noble youth, the serpent that did sting thy father's life now wears hiis crown." (1.5.45-47)
Gertrude' s infidelity after her king' s death
"So to seduce!- won to his shameful lust the will of my most seeming-virtuous queen." (1.5.52-3) "But virtue, as it never be moved, though lewdness court it in a shape of heaven, so lust, though to a radiant angel linked, will sate itself in a celestial bed and prey on garbage." (1.5.60-4)
Prince Hamlet is confronted by the ghost of his father, former king of Denmark, who reveals him a message.
The ghost calls Hamlet to action.
"Let not the royal bed of Denmark be a couch for luxury and damned incest. But howsomever thou pursues this act, taint not thy mind, nor let thy soul contrive against thy mother aught." (1.5.89-93)
The ghost reveals that the adulterate beast, Claudius, Hamlet's uncle, poured poison in the king's ear, thus taking his life, his crown, his queen all at once.
Hamlet proposes an oath.
"Propose the oath, my lord." (1.5.173)
"Never to speak of this that you have seen. Swear by my sword." (1.5.174-5)
The ghost also remarks on how his seeming-virtuous queen is in fact a lustful person who wouldn't mind switching from a kingly loving marriage to garbage.
Hamlet' s secret plan
The ghost moves on to call Hamlet to action. He tells Hamlet to avenge his death by killing Claudius. The ghost warns Hamlet not to do anything to his mother, but to "leave her to Heaven". The ghost disappears. All along, Hamlet reflects on his hate for his mother, and prepares to take up the vow that he made for his father.
Horatio and Marcellus walk in, worried about Hamlet. Hamlet reveals everything the ghost said and demands that his comrades swear by his sword.
Hamlet begins to tell that he might begin to act insane in the future, and ask his friends to promise they will never give the fact that they know about all of this.
"That you know aught of me - this not to do swear, so grace and mercy at your most need help you." (1.5.201-2)