How we cite our quotes: All quotations are from Taxi Driver.
Quote #1
PASSENGER: I'm gonna kill her. What do you think of that? Hmm? I said "What do you think of that?" Don't answer. You don't have to answer everything. I'm gonna kill her. I'm gonna kill her with a .44 Magnum pistol. I have a .44 Magnum pistol. I'm gonna kill her with that gun. Did you ever see what a .44 Magnum pistol can do to a woman's face? I mean it'll f***in' destroy it. Just blow her right apart.
This disturbs Travis, but it also presages his own rage. The passenger might not actually kill his wife, and this might be just a violent fantasy, but it's still disorienting. Travis isn't mad about adultery, but he is mad at a woman and he does have murderous impulses—and that might be why this encounter affects him so much. He senses a bit of himself in the sick passenger.
Quote #2
TRAVIS: Some fleet driver for Bell just got cut up. Just heard it on the radio.
DOUGH BOY: Stick-up?
TRAVIS: No, just some crazy f***er. Cut half his ear off.
This highlights how dangerous Travis' job really is. Like the other cab drivers, he could fall victim to the full nihilistic rage of the city, and can get killed at random. It helps us understand his own negative feelings more clearly.
Quote #3
DOUGH BOY: You run all over town, don't you?
TRAVIS: Yeah.
DOUGH BOY: You handle some pretty tough customers, huh?
TRAVIS: Yeah, I have.
DOUGH BOY: You carry a piece? You need one? If you ever need one, I know a fellow that can get you a real nice deal.
WIZARD: I never use mine. I'm conservative. But it's a good thing to have just as a threat.
This is ironic, because Travis will take their advice, but he won't get the guns for self-protection. He'll actually plan the harm of innocent people, like Charles Palantine.
Quote #4
TRAVIS: The idea had been growing in my brain for some time. True force. All the king's men cannot put it back together again.
The "king's men" won't be able to put anything back together again because Travis will smash things so thoroughly by killing Palantine (which he doesn't actually do, in the end). There's no moral purpose to his action at all—he wants to kill a presumed "man of the people" purely out of hate and rage. He holds all of America and all of humanity in condemnation.
Quote #5
ANDY: There you go—a supreme high re-sale weapon. Look at that. Look at that. That's a beauty. I could sell those guns to some jungle bunny in Harlem for five hundred bucks. But I just deal high-quality goods to the right people. How about that? This might be a little too big for practical purposes in which case for you, I'd recommend .38 snub nose. Look at this. Look at it. That's a beautiful little gun. It's nickel-plated, snub nose, otherwise the same as the service revolver. That'll stop anything that moves. The Magnum—they use that in Africa for killin' elephants. That .38—it's a fine gun. Some of these guns are like toys. That .38—you go out and hammer nails with it all day, come back and it will cut dead center on target every time. It's got a really nice action to it and a heck of a whallop. You interested in a automatic? It's a Colt .25 Automatic. It's a nice little gun. It's a beautiful little gun. It holds six shots in the clip, one shot in the chamber, if you're dumb enough to put a round in the chamber. Here, look at this. 380 Walther, holds eight shots in the clip. That's a nice gun. Now that's a beautiful little gun. Look at that. During World War II, they used this gun to replace the P38. Just given out to officers. Ain't that a little honey?
The illegal gun dealer, Easy Andy, clearly relishes guns—and uses more than a little racism in his sales pitch, besides. It's clear that he doesn't care what Travis does with these guns—he's not interested in the moral consequences of selling illegal firearms.
Quote #6
TRAVIS: Listen you f***ers, you screwheads. Here's a man who would not take it anymore. Who would not let—listen you f***ers, you screwheads. Here is a man who would not take it anymore. A man who stood up against the scum, the c***s, the dogs, the filth, the s***. Here is someone who stood up. Here is... [draws gun]. You're dead.
Travis is rehearsing his angry message to the world, trying to stylize his intended murders as an act of heroic resistance to a corrupt humanity. This is one of the points in the movie when we realize how crazy he really is.
Quote #7
TRAVIS: I don't screw and f*** with a bunch of killers and junkies the way you do. You call that being hip? What world you from?
IRIS: Who's a killer?
TRAVIS: Sport's a killer, that's who.
IRIS: Sport never killed nobody.
TRAVIS: He killed somebody.
We don't know whether Sport's actually killed somebody—we just know he's a really bad guy. The irony is that Travis will kill somebody (Sport) and has been planning an act of political mayhem (shooting Palantine).