William Parcher (Ed Harris): You see, John, what distinguishes you is that you are, quite simply, the best natural code breaker I have ever seen.

Nash: I find that polishing my interactions in order to make them sociable requires a tremendous effort. I have a tendency to expedite information flow by being direct. Often I don't get a good result.
Alicia: Try me.
Nash: I find you very attractive. Your aggressive moves toward me indicate you feel the same. Still ritual requires that we continue a number of platonic activities before we can have intercourse. But all I really want to do is have sex with you as soon as possible.
Are you going to slap me now?

Alicia: (kisses Nash in the mouth) How was that result?

Marcee Herman (Vivien Cardone): What ya doing?
Nash: I am attempting to isolate patterned reoccurrences across periodicals over time. And you?
Marcee: You talk funny, Mr. Nash.
Nash: Do I know you?
Marcee: My Uncle says you're very smart, but not very nice so I shouldn't pay any attention if you're mean to me.
Nash: And who might that uncle be?
Charles: The prodigal roommate returns.

Nash: I've met a girl.
Charles: An actual human girl? Homo sapien, biped?
Nash: And contrary to all probabilities, she finds me attractive on a number of different levels.
Charles: That's wonderful. Although there's no accounting for taste.
Nash: Do I marry her? I mean, it all seems to add up . . . But how do you know for sure?
Charles: Nothing's ever for sure. That's the only sure thing I know.

Nash: Alicia, does our relationship warrant long-term commitment? I need proof, some kind of verifiable, empirical data.
Alicia: I'm sorry, just give me a moment to redefine my girlish notions of romance.
A proof. Verifiable data. All right, how big is the universe?

Nash: Infinite.
Alicia: How do you know?
Nash: I know because all the data indicates that it's infinite.
Alicia: But it hasn't been proven yet. You haven't seen it.
Nash: No.
Alicia: Then how do you know for sure?
Nash: I don't. I just believe it.
Alicia: It's the same with love, I guess... Now the part you don't know is if I want to marry you.

Nash: So what am I now? A spy?

Parcher: I understand. Better than you can possibly imagine.

Nash: I'll just quit.
Parcher: No. You won't.
Nash: Why the hell not?
Parcher: Because I keep the Russians from knowing you work for us. If you quit working for me, I quit working for you.

Nash: ...And so we see that if the zeroes of the Riemann zeta function correspond to singularities in the space time then conventional number theory breaks down in the face of relativistic exploration... Sometimes, our expectations are betrayed by the numbers... And variables are impossible to assign any rational value...

Dr. Rosen (Christopher Plummer): Go easy. The Thorazine takes a little while to wear off... I'm sorry about the restraints, but you have a hell of a right hook.
Nash: Where am I?
Rosen: MacArthur Psychiatric Hospital.
Nash: I find that highly unlikely.
. . . This is a mistake. My work is nonmilitary in application.

Rosen: What work is that, John? Nash: I don't know anything, alright?
Rosen: There's no good in keeping secrets.

Nash: The prodigal roommate revealed! Saw my name on the lecture slate? You lying son of a bitch! How do you say Charles Herman in Russian?
Rosen: Who are you talking to, John? There's no one there.

Rosen: Which is more likely, that your husband, a mathematician with no military training, is a government spy feeling the Russians...Or that he has lost his grip on reality?

Rosen: Imagine if you suddenly learned that the people, the places, the moments most important to you were not gone, not dead, but worse, had never been. What kind of hell would that be?

Alicia: Often what I feel is obligation, or guilt over wanting to leave, or rage against John, against God. But then I look at him and I force myself to see the man I married. And he becomes that man. He's transformed into someone I love. And then I'm transformed into someone who loves him. It's not all the time. But it's enough.
. . .
Nash: Have you said hello to Harvey?
Sol: John, I-
Nash: Relax. What's good being nuts if you can't have a little fun?
Sol: Jesus, John.

Nash: What do people do?
Alicia: . . . It's called life, John. Activities available; just add meaning.

She never gets old.

Alicia: You want to know what's real? This...this is real.
I need to believe...that something extraordinary is possible.

Nash: Hello, Martin.
Hansen: Jesus Christ.
Nash: No. I don't have that one. My savior complex takes a different form.

Nash: And then, on the way home, Charles was there again... Sometimes I miss talking to him. Maybe Rosen is right. Maybe I have to think about going to the hospital.
Alicia: Maybe try again tomorrow.

Nash: You were good friends to me. The best. But I won't talk to you again... Or you either, baby girl. Goodbye.
. . .
Nash: I've gotten used to ignoring them and I think, as a result, they've kind of given up on me. I think that's what it's like with all our dreams and our nightmares, Martin, we've got to keep feeding them for them to stay alive.

Parcher: Ladies and gentlemen, the great John Nash!

Student: Did you just solve Riemann?
Nash: This analogue to Frobenius only works for a sporadic family of noncummutative extensions. So, no. But I'm making progress.
Student: You're John Nash, right? I've been studying your equilibrium. To come up with something totally original the way you did... I've been developing a theory. I believe I can show that Galois extensions are covering spaces. That everything is connected. That it's all one subject. Maybe you could take a look.
Nash: When is the last time you ate? You know, food?

Thomas King: Professor Nash?
Nash: (to one of his students) Do you see him?
Student: Yeah.
Nash: You'll forgive me. I'm always suspicious of new people.
. . .
Nash: So you came here to see if I was crazy. To see if I'd screw everything up if I actually won. Maybe dance on the podium or strip naked and squawk like a chicken.
King: Something like that, yes.
Nash: Would I embarrass you? Yes, I suppose it's possible. You see, I am crazy. I take the newer medications, but I still see things that are not here. I just choose not to acknowledge them. Like a diet of the mind. I do not indulge certain appetites, like my appetite for patterns. And perhaps my appetite to imagine and to dream.

Nash: I've always believed in numbers. In the equations and logics that lead to reason... I've made the most important discovery of my life. It is only in the mysterious equations of love that any logic or reason can be found. Perhaps it is good to have a beautiful mind. But it is a better gift to discover a beautiful heart . . . I'm only here tonight because of you. You're the only reason I am... you're all my reasons.

Alicia: What is it? What's wrong?
Nash: Nothing. Nothing at all.