"O, what a rogue and peasant slave am I!
Is it not monstrous that this player here,
But in a fiction, in a dream of passion,
Could force his soul so to his own conceit
That from her working all his visage wann'd,
Tears in his eyes, distraction in's aspect,
A broken voice, and his whole function suiting
With forms to his conceit? and all for nothing!
For Hecuba!
What's Hecuba to him, or he to Hecuba,
That he should weep for her? What would he do,
Had he the motive and the cue for passion
That I have?" (2.2.58)

So, while Hamlet is flipping out over papa-ghost, an acting troupe rolls into town. They finally show him the real way to express emotions. See, Hamlet is a little concerned that he spends too much time over-thinking things.

Which, if you've seen the play, you know he does. That's kind of one of his defining characteristics: annoyingly over-analyzing and over-agonizing about stuff.

This super duper famous soliloquy calls into question the power of performance, the value of being able to express emotion, and, more importantly, the value of action. After this scene, Hamlet is convinced the best way to solve the murder mystery surrounding his father's death—and get one step closer to ending the ghost's haunting—is to put on a play that will hopefully move Claudius (the dude Hammy suspects killed his dad) to reveal…

Something. Guilt or remorse or some outward sign that he did it. Theatre during the Renaissance literally had the ability to save the day. Well, we mean, this was a tragedy that ended in a lot of blood. But you get the point, right?

The awesome thing about this passage's focus on the power of theatre is that, as Hamlet is soliloquizing, he's also supplying a string of rhetorical questions for the audience to ponder. In short, Hamlet's aha moment works as a rhetorical argument to convince himself to act.

By proxy. Through, you know, other actors. This is so meta our heads hurt. Have you figured out why English teachers are so obsessed with this play yet?