The Killing Joke contains a number of the greatest monologues in Batman (and comic book, and perhaps print media) history, and it's a bit difficult to not quote the whole thing. The most important monologues, however, are such:
Batman: "Hello. I came to talk. I've been thinking lately. About you and me. About what's going to happen to us, in the end. We're going to kill each other, aren't we? Perhaps you'll kill me. Perhaps I'll kill you. Perhaps sooner. Perhaps later. I just wanted to know that I'd made a genuine attempt to talk things over and avert that outcome. Just once. Are you listening to me? It's life and death I'm discussing here. Maybe my death... maybe yours. I don't fully understand why ours should be such a fatal relationship, but I don't want your murder on my... hands..."
Joker: "So... I see you received the free ticket I sent you. I'm glad. I did so want you to be here. You see, it doesn't matter if you catch me and send me back to the asylum... Gordon's been driven mad. I've proved my point. I've demonstrated there's no difference between me and everyone else! All it takes is one bad day to reduce the sanest man alive to lunacy. That's how far the world is from where I am. Just one bad day.
You had a bad day once, am I right? I know I am. I can tell. You had a bad day and everything changed. Why else would you dress up like a flying rat? You had a bad day, and it drove you as crazy as everybody else... only you won't admit it! You have to keep pretending that life makes sense, that there's some point to all this struggling! God, you make me want to puke.
I mean, what is it with you? What made you what you are? Girlfriend killed by the mob, maybe? Brother carved up by some mugger? Something like that, I bet. Something like that...
Something like that happened to me, you know. I... I'm not exactly sure what it was. Sometimes I remember it one way, sometimes another... if I'm going to have a past, I prefer it to be multiple choice! Ha ha ha!
But my point is... my point is, I went crazy. When I saw what a black, awful joke the world was, I went crazy a coot! I admit it! Why can't you? I mean, you're not unintelligent! You must see the reality of the situation. Do you know how many times we've come close to World War Three over a flock of geese on a computer screen? Do you know what triggered the last World War? An argument over how many telegraph poles Germany owed its war debt creditors! Telegraph poles! Ha ha ha ha ha!
It's all a joke! Everything everybody ever valued or struggled for... it's all a monstrous, demented gag! So why can't you see the funny side?
Why aren't you laughing?"
Batman: "I spoke to Commissioner Gordon before I came in here. He's fine. Despite all your sick, vicious little games, he's as sane as he ever was! So maybe ordinary people don't always crack. Maybe there isn't any need to crawl under a rock with all the other slimey things when trouble hits. Maybe it was just you, all the time!"
Batman: "Don't you understand? I don't want to hurt you. I don't want either of us to end up killing the other. But we're both running out of alternatives... and we both know it. Maybe it all hinges on tonight. Maybe this is our last chance to sort this bloody mess out. If you don't take it, then we're both locked onto a suicide course. Both of us. To the death. It doesn't have to end like that. I don't know what it was that bent your life out of shape, but who knows? Maybe I've been there too. Maybe I can help. We could work together. I could rehabilitate you. You needn't be out there on the edge anymore. You needn't be alone. We don't have to kill each other. What do you say?"
Joker: "No. I'm sorry, but... no. It's too late for that. Far too late. Hahaha. You know, it's funny. This situation. It reminds me of a joke..."
Joker: "See, there were these two guys in a lunatic asylum. And one night, they decide they don't like living in the asylum anymore. They decide they're going to escape! So, like, they get up onto the roof, and there, just across this narrow gap, they see the rooftops of the town, stretching away into the moonlight. Stretching away to freedom. Now, the first guy, he jumps right across with no problem. But his friend, his friend daren't make the leap. Y'see... y'see, he's afraid of falling. So then the first guy has an idea... He says, 'Hey, I have a flashlight with me! I'll shine it across the gap between the buildings. You can walk across the beam and join me!' But the second guy just shakes his head. He suh-says... he says 'Wh-what do you think I am? Crazy? You'd turn it off when I was halfway across!'"