A man creates a strange system to help him remember things; so he can hunt for the murderer of his wife without his short-term memory loss being an obstacle.

Leonard Shelby: We all lie to ourselves to be happy.
Leonard Shelby: I have to believe in a world outside my own mind. I have to believe that my actions still have meaning, even if I can't remember them. I have to believe that when my eyes are closed, the world's still there. Do I believe the world's still there? Is it still out there?... Yeah. We all need mirrors to remind ourselves who we are. I'm no different.
Leonard Shelby: [running] OK, so what am I doing?
[sees Dodd also running]
Leonard Shelby: Oh, I'm chasing this guy.
[Dodd shoots at Leonard]
Leonard Shelby: No... he's chasing me.
Leonard Shelby: Memory can change the shape of a room; it can change the color of a car. And memories can be distorted. They're just an interpretation, they're not a record, and they're irrelevant if you have the facts.
[last lines]
Leonard Shelby: Now... where was I?
Leonard Shelby: I can't remember to forget you.
Natalie: What's the last thing that you do remember?
Leonard Shelby: My wife...
Natalie: That's sweet.
Leonard Shelby: ...dying.
Leonard Shelby: I'm not a killer. I'm just someone who wanted to make things right. Can't I just let myself forget what you've told me? Can't I just let myself forget what you've made me do. You think I just want another puzzle to solve? Another John G. to look for? You're John G. So you can be my John G... Will I lie to myself to be happy? In your case Teddy... yes I will.
Leonard Shelby: I don't even know how long she's been gone. It's like I've woken up in bed and she's not here... because she's gone to the bathroom or something. But somehow, I know she's never gonna come back to bed. If I could just... reach over and touch... her side of the bed, I would know that it was cold, but I can't. I know I can't have her back... but I don't want to wake up in the morning, thinking she's still here. I lie here not knowing... how long I've been alone. So how... how can I heal? How am I supposed to heal if I can't... feel time?
Teddy: You don't want the truth. You make up your own truth.
Leonard Shelby: We all need mirrors to remind ourselves who we are. I'm no different.
Leonard Shelby: If we can't make memories, we can't heal.
Natalie: But even if you get revenge you're not gonna remember it. You're not even going to know that it happened.
Leonard Shelby: My wife deserves vengance. Doesn't make a difference whether I know about it. Just becuase there are things I don't remember doesn't make my actions meaningless. The world doesn't just disappear when you close your eyes, does it? Anyway, maybe I'll take a photograph to remind myself, get another freaky tattoo.
Natalie: Tell me about her again.
Leonard Shelby: Why?
Natalie: Because you like to remember her.
Leonard Shelby: She was beautiful. To me, she was perfect.
Natalie: No, don't just recite the words. Close your eyes... and remember her.
Leonard Shelby: You can just feel the details. The bits and pieces you never bothered to put into words. And you can feel these extreme moments... even if you don't want to. You put these together, and you get the feel of a person. Enough to know how much you miss them... and how much you hate the person who took them away.
Leonard Shelby: Remember Sammy Jankis.
Leonard Shelby: There are things you know for sure.
Natalie: Such as?
Leonard Shelby: I know what that's going to sound like when I knock on it. I know that's what going to feel like when I pick it up. See? Certainties. It's the kind of memory that you take for granted.
[finding a beaten man in his closet]
Leonard Shelby: ...who did this to you?
Dodd: What?
Leonard Shelby: Who did this to you?
Dodd: You did.
[repeated line]
Leonard Shelby: I have this condition.
Natalie: Is that what your little note says? It must be hard living your life off a couple of scraps of paper. You mix your laundry list with your grocery list you'll end up eating your underwear for breakfast.
Teddy: Hey! Hey, that's not your car!
Leonard Shelby: [takes a picture of the Jaguar] It is now.
Teddy: Jesus Chri- you can't take it!
Leonard Shelby: Why not?
Teddy: Because the guy you killed owns it; somebody will recognize it!
Leonard Shelby: Well, I rather be mistaken for a dead guy than a killer.
Leonard Shelby: These tracks are just a few days old.
Teddy: What are you, Pocahontas?
Leonard Shelby: I don't think they'd let someone like me carry a gun.
Teddy: I fucking hope not.
Leonard Shelby: I found you, you fuck.
Teddy: [checking Leonard's pulse] You're living.
Leonard Shelby: Only for revenge.
Sammy Jankis: [after being shocked] What the fuck?
Doctor: It's a test, Sammy.
Sammy Jankis: [flipping him the bird] Test this, you fucking quack!
Burt Hadley: Oh shit. This is the wrong room. You're in 304 now. I'm sorry. I fucked up.
Leonard Shelby: This is not my room?
Burt Hadley: No, come on, let's go.
Leonard Shelby: Why is this my handwriting?
Burt Hadley: ...This was your room, but now you're in 304.
Leonard Shelby: When was I in here?
Burt Hadley: Last week. But then I rented you another room on top of it.
Leonard Shelby: Why?
Burt Hadley: Business is slow. I mean, I told my boss about the - your condition and stuff, and he said try and rent him another room.
Leonard Shelby: So how many rooms am I checked into in this shit-hole?
Burt Hadley: Just two, so far.
Leonard Shelby: Well, at least you're being honest about ripping me off.
Burt Hadley: Well, you're not gonna remember anyway.
Leonard Shelby: You don't have to be *that* honest, Burt.
Burt Hadley: Leonard, always get a receipt.
Leonard Shelby: That's good advice. I'll have to write that down.
Teddy: Was he scared?
Leonard Shelby: Yeah, I think it was your sinister moustache.
Teddy: Fuck you.
Teddy: So you lie to yourself to be happy. There's nothing wrong with that. We all do it.
Leonard Shelby: I don't want your fucking money.
Jimmy Grantz: Then what? What do you want?
Leonard Shelby: I want my fucking life back!
Teddy: You don't know who you are anymore.
Leonard Shelby: Of course I do. I'm Leonard Shelby. I'm from San Francisco.
Teddy: No, that's who you were. Maybe it's time you started investigating yourself.
Teddy: You know how many towns, how many guys called James G? Or John G? Shit, Leonard, I'm a fuckin' John G.
Leonard Shelby: Your name's Teddy.
Teddy: My *mother* calls me Teddy.
Leonard Shelby: Hi. Uh, Lincoln Street?
Waiter: Oh, you just take the main road...
Leonard Shelby: Hang on, let me write this down.
Waiter: Oh, it's easy. You just...
Leonard Shelby: Trust me, I need to write this down.
Teddy: You know, I've had more rewarding friendships than this one. Although I do get to keep telling the same jokes.
Leonard Shelby: You know, I can remember so much. The feel of the world... her.
[sighs]
Leonard Shelby: She's gone. And the present is trivia, which I scribble down as fucking notes.
[flashback]
Leonard Shelby: How can you read that again?
Leonard's Wife: It's good.
Leonard Shelby: Yeah, but you read it like a thousand times.
Leonard's Wife: I enjoy it.
Leonard Shelby: I always thought the pleasure of a book was wanting to know what comes next.
Leonard's Wife: Hey, don't be a prick. I'm not reading it to annoy you, I enjoy it. Just let me read... please.
[smiles at him]
Leonard Shelby: I always thought the joy of reading a book is not knowing what happens next.
Leonard Shelby: Beg my wife's forgiveness, before I blow
[pause]
Leonard Shelby: your brains out.
Leonard Shelby: Facts, not memories. That's how you investigate. I know, it's what I used to do.
[about Leonard's condition]
Burt Hadley: What's it like?
Leonard Shelby: It's like waking. Like you just woke up.
Burt Hadley: That must suck.
Leonard Shelby: My wife deserves revenge, whether I know about it or not.
Leonard Shelby: I take it I've told you about my condition.
Teddy: Only every time I see ya.
Natalie: You sad, sad freak. I can say whatever the fuck I want, and you won't remember. We'll still be best friends. Or maybe even lovers.
[repeated line]
Leonard Shelby: Awake. Where am I?
Leonard Shelby: Sammy Jankis wrote himself endless notes. But he'd get mixed up. I've got a more graceful solution to the memory problem. I'm disciplined and organized. I use habit and routine to make my life possible. Sammy had no drive. No reason to make it work.
Natalie: You know what? I think I'm gonna use you. I'm telling you now because I'll enjoy it so much more if I know that you could stop me if you weren't such a fucking freak!
Teddy: Someone has to pay, Lenny. Somebody always pays.
Teddy: You're not a killer.
[pinches Leonard's cheeks]
Teddy: That's why you're so good at it.
Leonard Shelby: [looking at a near-empty bottle of alcohol in his hand] Hmmm. I don't feel drunk.
Leonard Shelby: If we talk for too long, I'll forget how we started. Next time I see you, I'm not gonna remember this conversation. I don't even know if I've met you before.
[pause]
Leonard Shelby: I've told you this before, haven't I?
Teddy: It's beer o'clock, and I'm buying.
Leonard Shelby: It's just an anonymous room. There's nothing in the drawers. But you look anyway. Nothing except the Gideon bible, which I, of course, read religiously.
Leonard Shelby: When I looked into his eyes I thought I saw recognition. Now I know. You fake it. If you think you're supposed to recognize somebody you, you just pretend. You bluff it to get a pat on the head from the doctors. You bluff it to seem less like a freak.
Leonard Shelby: I was the only guy who disagreed with the cops - and I had brain damage.
Teddy: Finished playing with yourself there, Lenny?
Teddy: You really want to get this guy, don't you?
Leonard Shelby: He killed my wife. He took away my fucking memory. He destroyed my ability to live.
Leonard Shelby: Probably burned truck loads of your stuff before. Can't remember to forget you.
Sammy Jankis: That's a test? Where were you guys when I did my CPA?
[Leonard hits Teddy in the back of his head with his camera]
Teddy: Lenny! That shit kills!
Leonard Shelby: I meet Sammy through work. Insurance. I was an investigator. I'd investigate the claims to see which ones were phony. I had to see through people's bullshit. It was useful experience, 'cause now it's my life.
Teddy: Nice shot, Liebowitz.
Leonard Shelby: [while walking through a parking lot, Teddy stops at his dilapidated Chevrolet] My car.
Teddy: [laughs] This is your car.
Leonard Shelby: [holds up a picture of the Jaguar with the caption My Car] Oh, you're in a playful mood. It's not good for you to make fun of somebody's handicap.
Teddy: Just trying to have a little fun.
Natalie: You know what one of the reasons for short term memory loss is? Venereal disease. Maybe your cunt of fucking a wife sucked one too many diseased cocks and turned you into a fucking retard.
[wields a crowbar in his hand]
Leonard Shelby: Strip!
[Jimmy takes off his shirt]
Leonard Shelby: Take off your pants too.
Jimmy Grantz: Why?
Leonard Shelby: I don't want to get blood on them.
Teddy: But when you killed him I, I was so convinced that you'd remember. But it didn't stick... like nothin' ever sticks, like this won't stick.
Leonard Shelby: Natalie, right?
[Holds up photo of a bloody face, labeled "Dodd"]
Leonard Shelby: Who the fuck is Dodd?
Natalie: [Looks at photo] Guess I don't have to worry about him anymore.
Teddy: We found him, you killed him!... But you didn't remember.
[first lines]
Leonard Shelby: [voiceover] So where are you? You're in some motel room. You just - you just wake up and you're in - in a motel room. There's the key. It feels like maybe it's just the first time you've been there, but perhaps you've been there for a week, three months. It's - it's kind of hard to say. I don't - I don't know. It's just an anonymous room.
Natalie: Get rid of Dodd for me. Kill him. I'll pay you.
Leonard Shelby: Are you crazy? I'm not gonna kill someone for money.
Natalie: What then? Love? What would you kill for? You'd kill for your wife, wouldn't you?
Leonard Shelby: That's different!
Natalie: Not to me, I wasn't fucking married to her!
[talking on the phone about Sammy Jankis' attempts to learn through repitition]
Leonard Shelby: Sammy had no drive, no reason to make it work.
[listens and looks at his tattoo reading "John G. raped and murdered my wife"]
Leonard Shelby: Me? Yeah, I got a reason.
Teddy: When she offers to help, it'll be for her own reasons. I'm not lying. Take my pen, write this down. Do not trust her.