"I am thy father’s spirit, Doomed for a certain term to walk the night And for the day confined to fast in fires Till the foul crimes done in my days of nature." (Act 1, Sc 5)
"Murder most foul, as in the best it is. But this most foul, strange and unnatural…A serpent stung me. So the whole ear of Denmark Is by a forgèd process of my death Rankly abused. But know, thou noble youth, The serpent that did sting thy father’s life Now wears his crown." (Act 1, Sc 5)
"O my prophetic soul! My uncle?" (Act 1, Sc 5)
"And thy commandment all alone shall live Within the book and volume of my brain, Unmixed with baser matter. Yes, by heaven! O most pernicious woman! O villain, villain, smiling, damnèd villain! My tables!—Meet it is I set it down That one may smile, and smile, and be a villain. At least I’m sure it may be so in Denmark. (writes) So, uncle, there you are. Now to my word." (Act 1, Sc 5)
May be the devil, and the devil hath power T' assume a pleasing shape. Yea, and perhaps Out of my weakness and my melancholy, As he is very potent with such spirits, Abuses me to damn me. I’ll have grounds More relative than this. The play’s the thing Wherein I’ll catch the conscience of the king. (Act 2, Sc 2)
Hamlet meets the ghost who reveals he is the spirit of King Hamlet (his father) and tells Hamlet that Claudius killed him and tells Hamlet to seek revenge for his murder.
"But, oh, what kind of prayer is there for me? 'Dear Lord, forgive me for my horrible murder?'" (Act 3, Sc 3)
"So is it really revenge for me if I kill Claudius right when he is confessing his sins, in perfect condition for a trip to heaven? No. Away, sword, and wait for a better moment to kill him." (Act 3 scene 3, pg. 4 )
Hamlet agrees to plot the revenge against Claudius in order to avenge his father.
"Do not forget. This visitation Is but to whet thy almost blunted purpose. But look, amazement on thy mother sits. O, step between her and her fighting soul. Conceit in weakest bodies strongest works. Speak to her, Hamlet." (Act 3, Sc 4)
"Have you come to scold your tardy son for straying from his mission, letting your important command slip by? Tell me!" (Act 3, Sc 4)
Hamlet still doesn’t know if the ghost is really his father telling the truth about his death or a demon lying in order to hurt him. So to prove that the ghost’s story is true, he decides, in order to catch Claudius in his guilt for killing King Hamlet he would stage a play where the circumstances of King Hamlet’s death are played out and if Claudius appears upset then he is guilty and the ghost was right.
Hamlet tells Horatio to watch Claudius’s reaction to the play, and attends the play with Ophelia, the King, Polonius and his mother and when Claudius sees the play King getting killed Claudius exclaims for the show to end and Hamlet know he is guilty. After the show everyone is upset, Gertrude goes to her room and Hamlet tries to complete his task of revenge and kill Claudius after the play, but he is praying and Hamlet stops himself as he doesn’t want Claudius to die sin free.
Hamlet then attempts to make his point of revenge clear to his mother but King Hamlet’s ghost stops him and reminds him that he still hasn’t taken revenge on Claudius.
After coming across soldiers who say they’re fighting over a little plot of land with little significance, Hamlet doesn’t understand why they would fight such a great battle with such little gain. But then reflects on his own situation, where he has everything to gain by killing Claudius and getting revenge, and yet hasn’t done so. He is angry at himself and vows to be more prudent with sticking to his revenge plot.
"How all occasions do inform against me, And spur my dull revenge! What is a man if his chief good and market of his time be but to sleep and feed? A beast, no more. Sure, he that made us with such large discourse, Looking before and after, gave us not that capability and godlike reason to fust in us unused. Now, whether it be Bestial oblivion, or some craven scruple." (Act 4, Sc. 4)
Whereon the numbers cannot try the cause, Which is not tomb enough and continent To hide the slain? Oh, from this time forth, My thoughts be bloody, or be nothing worth! (Act 4, Sc 4)