In Hamlet, Act 4, Scene 4, Lines 33-65, explain the significance of this soliloquy to the theme of revenge.
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 Of thinking too precisely on th' event— A thought which, quartered, hath but one part wisdom And ever three parts coward—I do not know Why yet I live to say “This thing’s to do,” Sith I have cause and will and strength and means To do ’t. Examples gross as earth exhort me. Witness this army of such mass and charge Led by a delicate and tender prince, Whose spirit with divine ambition puffed Makes mouths at the invisible event, Exposing what is mortal and unsure To all that fortune, death, and danger dare, Even for an eggshell. Rightly to be great Is not to stir without great argument, But greatly to find quarrel in a straw When honor’s at the stake. How stand I then, That have a father killed, a mother stained, Excitements of my reason and my blood, And let all sleep—while, to my shame, I see The imminent death of twenty thousand men, That for a fantasy and trick of fame Go to their graves like beds, fight for a plot 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!
Oh no! I had to edit the question to italicise the title of this play and during the course of editing it, I am afraid that the quote was changed from blank verse to prose! Sorry about that.
However, let us remind ourselves what is happening in this scene. Hamlet sees a mass of Norwegian troops, led by Fortinbrass, crossing Danish territory, on their way to Poland to fight. What causes Hamlet to think about his own situation is the way in which these soldiers are travelling to fight over "a little patch of ground / That hath in it no profit but the name." The Poles and the Norwegians will fight for it simply to win "honour." Hamlet is disgusted by this.
However, in this soliloquy, which is actually Hamlet's final soliloquy in the play, Hamlet compares the action of Fortinbras to his own. This is a similar sceen to Act II scene 2 when Hamlet compared himself to the actor, because the comparison leaves him feeling ashamed. He sees Fortinbras ready to "find quarrel in a straw / When honour's at the stake." With so little reason, Fortinbras shows himself always ready to prove and fight for his honour. If Fortinbras is so willing and ready to fight openly for his honour over such a little cause, where does that leave Hamlet?:
How stand I then
That have a father kill'd, a mother stain'd,
Excitements of my reason, and my blood,
And let all sleep, while to my shame I see
The imminent death of twenty thousand men,
That for a fantasy and trick of fame
Go to their graves like beds, fight for a plot
Whereon the numbers cannot try the cause...
Hamlet is ashamed by the attitude of the soldiers, who for so little reason go to die, whereas he has done nothing to fight for his own honour, when he has so much more reason to fight. He resolves to have bloody thoughts from now on.