Revenge

1.5.12 GHOST: So art thou to revenge when thou shalt hear.
 * Before the ghost even tells his story, he tells Hamlet that by the end of his dialogue he must be ready to seek revenge.
 * Hamlet responds with "What?" (1.5.13), which illustrates that at this point he has no idea as to what the Ghost will be telling him and that he is still in a state of shock.

1.5.31 GHOST: Revenge his foul and most unnatural murder.
 * The Ghost is constantly telling Hamlet to seek revenge upon Claudius for Hamlet Sr.'s murder.
 * The constant mention of "revenge" had a strong influence on Hamlet who then contemplates what to do for the rest of the play.
 * The Ghost seems almost forceful when trying to tell Hamlet about revenge.

1.5.35-37 HAMLET: Haste me to know 't, that I, with wings as swift/As meditation or the thoughts of love,/May sweep to my revenge.
 * Tells the Ghost that he will take action quickly, which is ironic because he spends the entire play deciding what to do about his father's murder.

1.5.38-41 GHOST: I find thee apt;/And duller shouldst thou be than the fat weed/That roots itself in ease on Lethe wharf,/Wouldst thou not stir in this.
 * Again, the Ghost is encouraging in a forceful manner that Hamlet does something about this newly gained knowledge about Hamlet Sr.'s death.
 * Manipulating Hamlet's emotions. Making him feel guilty if he were to not do anything about Claudius.
 * Persuade Hamlet to seek revenge.

1.5.91 GHOST: But, howsomever thou pursues this act,
 * The Ghost is telling Hamlet that he is going to take action.
 * Has already made the decision for Hamlet and shares what is expected of him as a loyal son.

2.2.610-616 HAMLET: O vengeance!/Why, what an ass am I! This is most brave,/That I, the son of a dear father murdered,/Prompted to my revenge by heaven and hell,/Must, like a whore, unpack my heart with words/And fall a-cursing like a very drab,/A scullion! Fie upon 't,foh!
 * Hamlet's long rant eventually leads to talk about seeking revenge again, where he realizes that he has just been standing around not actually doing anything.
 * Comes up with a plan to utilize the play and the actors to see whether or not Claudius actually killed Hamlet Sr.
 * Once again, Hamlet needs more evidence and convincing to take revenge.

3.3.77-83 HAMLET: Now might I do it pat. Now he is a-praying./And now I'll do 't. And so he goes to heaven./And so am I revenged. -- That would be scanned./A villain kills my father, and, for that,/I, his sole son, do this same villain send/To heaven.