Proof

by

David Auburn

Teachers and parents! Our Teacher Edition on Proof makes teaching easy.

Catherine Character Analysis

Catherine is the quick-witted, stubborn, and prickly protagonist of the play. Her father, Robert, was a famous mathematician, and when the play opens, he has recently died. Catherine (who is in her mid-twenties) has been caring for him for the past few years, and now that he’s gone, she has to figure out what to do with her life next. This becomes a point of contention when Catherine’s hectoring older sister, Claire, flies in from New York and suggests that Catherine isn’t mentally stable enough to live on her own, which Catherine forcefully rejects. A recurring tension in the play is whether Catherine has inherited her father’s mental illness—she’s definitely prone to depression, but it’s not clear whether it’s anything worse. For instance, when she speaks with her dead father, it might be normal grieving, but it might be a hallucination, and Catherine herself doesn’t even seem sure. What she is sure of (which she reveals near the end of the play) is that during the time she cared for her father, she wrote a complicated and groundbreaking mathematical proof, echoing the iconic work that Robert did when he was around her age. Initially, none of the other characters believe that she could have written the proof, including her father’s former student Hal, with whom Catherine has recently become romantically involved. While Claire thinks Catherine isn’t sane enough to have written it, Hal thinks she’s insufficiently educated (she dropped out of college to care for Robert). His dismissal of Catherine’s abilities reflects the rampant sexism among mathematicians, and it breaks Catherine’s trust, sending her into a tailspin. However, after reviewing the proof with some colleagues, Hal concludes that Catherine is telling the truth—she has written something that will change the field. The play ends with Hal and Catherine repairing their relationship, and it seems that Catherine will stay in Chicago and use the proof to catapult herself into a math career, just like her late father.

Catherine Quotes in Proof

The Proof quotes below are all either spoken by Catherine or refer to Catherine. For each quote, you can also see the other characters and themes related to it (each theme is indicated by its own dot and icon, like this one:
Genius and Mental Instability Theme Icon
).
Act One, Scene 1 Quotes

ROBERT: You see? Even your depression is mathematical. Stop moping and get to work. The kind of potential you have—

CATHERINE: I haven’t done anything good.

ROBERT: You’re young. You’ve got time.

CATHERINE: I do?

ROBERT: Yes.

CATHERINE: By the time you were my age you were famous.

Related Characters: Catherine (speaker), Robert (speaker)
Page Number: 10
Explanation and Analysis:

CATHERINE: You died a week ago […] You’re sitting here. You’re giving me advice. You brought me champagne.

ROBERT: Yes.

CATHERINE: Which means…

ROBERT: For you?

CATHERINE: Yes.

ROBERT: For you, Catherine, my daughter, who I love very much…It could be a bad sign.

Related Characters: Catherine (speaker), Robert (speaker)
Page Number: 13
Explanation and Analysis:

HAL: […] When your dad was younger than both of us, he made major contributions to three fields: game theory, algebraic geometry, and nonlinear operator theory. Most of us never get our heads around one. He basically invented the mathematical techniques for studying rational behavior, and he gave the astrophysicists plenty to work over too. Okay?

CATHERINE: Don’t lecture me.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Page Number: 17
Explanation and Analysis:

HAL: […] “Talking with students helps. So does being outside, eating meals in restaurants, riding buses, all the activities of ‘normal’ life. Most of all Cathy. The years she has lost caring for me […] her refusal to let me be institutionalized—her keeping me at home, caring for me herself, has certainly saved my life. Made writing this possible. Made it possible to imagine doing math again […] I can never repay her.”

Related Characters: Robert (speaker), Hal (speaker), Catherine
Page Number: 23
Explanation and Analysis:
Act One, Scene 2 Quotes

CLAIRE: Did you use that conditioner I bought you?

CATHERINE: No, shit, I forgot.

CLAIRE: It’s my favorite. You’ll love it, Katie. I want you to try it. […] It has jojoba […] It’s something they put in for healthy hair.

CATHERINE: Hair is dead […] It’s dead tissue. You can’t make it healthy.

CLAIRE: It makes my hair feel, look, and smell good. That’s the extent of my information about it. You might like it if you decide to use it.

Related Characters: Catherine (speaker), Claire (speaker)
Page Number: 24-25
Explanation and Analysis:
Act One, Scene 3 Quotes

CATHERINE: […] Later a mutual friend told [Gauss] the brilliant young man was a woman.

He wrote to her: “A taste for the mysteries of numbers is excessively rare, but when a person of the sex which, according to our customs and prejudices, must encounter infinitely more difficulties than men to familiarize herself with these thorny researches, succeeds nevertheless in penetrating the most obscure parts of them, then without a doubt she must have the noblest courage, quite extraordinary talents, and superior genius.”

(Now self-conscious) I memorized it…

Related Characters: Catherine (speaker), Gauss (speaker), Sophie Germain
Page Number: 36
Explanation and Analysis:
Act One, Scene 4 Quotes

CATHERINE: I know you mean well. I’m just not sure what I want to do. I mean to be honest you were right yesterday. I do feel a little confused. I’m tired. It’s been a pretty weird couple of years. I think I’d like to take some time to figure things out.

CLAIRE: You could do that in New York.

CATHERINE: And I could do it here.

CLAIRE: But it would be much easier for me to get you set up in an apartment in New York, and—

CATHERINE: I don’t need an apartment, I’ll stay in the house.

CLAIRE: We’re selling the house.

Related Characters: Catherine (speaker), Claire (speaker)
Page Number: 42-43
Explanation and Analysis:

CLAIRE: Living here with him didn’t do you any good. You said that yourself.

You had so much talent…

CATHERINE: You think I’m like Dad.

CLAIRE: I think you have some of his talent and some of his tendency toward…instability.

Related Characters: Catherine (speaker), Claire (speaker), Robert
Page Number: 45
Explanation and Analysis:
Act Two, Scene 1 Quotes

ROBERT: […] I’m not doing much right now. It does get harder. It’s a stereotype that happens to be true, unfortunately for me—unfortunately for you, for all of us.

CATHERINE: Maybe you’ll get lucky.

ROBERT: Maybe I will. Maybe you’ll pick up where I left off.

CATHERINE: Don’t hold your breath.

ROBERT: Don’t underestimate yourself.

Related Characters: Catherine (speaker), Robert (speaker), Hal
Page Number: 57
Explanation and Analysis:
Act Two, Scene 2 Quotes

CLAIRE: […] You wrote this incredible thing and you didn’t tell anyone?

CATHERINE: I’m telling you both now. After I dropped out of school I had nothing to do. I was depressed, really depressed, but at a certain point I decided, Fuck it, I don’t need them. It’s just math, I can do it on my own. So I kept working here. I worked at night, after Dad had gone to sleep. It was hard but I did it. […]

CLAIRE: Catherine, I’m sorry but I just find this very hard to believe.

Related Characters: Catherine (speaker), Claire (speaker), Robert
Related Symbols: Proof
Page Number: 60-61
Explanation and Analysis:

HAL: I’ll tell them we’ve found something, something potentially major, we’re not sure about the authorship; I’ll sit done with them. We’ll go through the thing carefully […] and figure out exactly what we’ve got. It would only take a couple of days, probably, and then we’d have a lot more information. […]

CATHERINE: You can’t take it …] You don’t waste any time, do you? No hesitation. You can’t wait to show them your brilliant discovery.

HAL: I’m trying to determine what this is.

CATHERINE: I’m telling you what it is.

HAL: You don’t know!

CATHERINE: I wrote it.

Related Characters: Catherine (speaker), Hal (speaker)
Related Symbols: Proof
Page Number: 63
Explanation and Analysis:

HAL: I’m a mathematician […] I know how hard it would be to come up with something like this. I mean it’s impossible. You’d have to be…you’d have to be your dad, basically. Your dad at the peak of his powers.

CATHERINE: I’m a mathematician too.

HAL: Not like your dad.

CATHERINE: Oh, he’s the only one who could have done this?

HAL: The only one I know.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Related Symbols: Proof
Page Number: 64
Explanation and Analysis:
Act Two, Scene 3 Quotes

CLAIRE: […] I probably inherited about one one-thousandth of my father’s ability. It’s enough.

Catherine got more, I’m not sure how much.

Related Characters: Claire (speaker), Catherine, Robert
Page Number: 68
Explanation and Analysis:
Act Two, Scene 4 Quotes

CATHERINE: “[…] In September the students come back and the bookstores are full. Let X equal the month of full bookstores. The number of books approaches infinity as the number of months of cold approaches four. I will never be as cold now as I will in the future. The future of cold is infinite. The future of heat is the future of cold. The bookstores are infinite and so are never full except in September…” […] It’s all right. We’ll go inside.

ROBERT: I’m cold.

CATHERINE: We’ll warm you up.

ROBERT: Don’t leave. Please.

CATHERINE: I won’t. Let’s go inside.

Related Characters: Catherine (speaker), Robert (speaker)
Page Number: 74
Explanation and Analysis:
Act Two, Scene 5 Quotes

HAL: […] Your dad dated everything. Even his most incoherent entries he dated. There are no dates in this.

CATHERINE: The handwriting—

HAL: —looks like your dad’s. Parents and children sometimes have similar handwriting, especially if they’ve spent a lot of time together.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Related Symbols: Proof
Page Number: 80
Explanation and Analysis:

HAL: Come on, Catherine. I’m trying to correct things.

CATHERINE: You can’t. Do you hear me?

You think you’ve figured something out? You run over here so pleased with yourself because you changed your mind. Now you’re certain. You’re so…sloppy. You don’t know anything. The book, the math, the dates, the writing, all that stuff you decided with your buddies, it’s just evidence. It doesn’t finish the job. It doesn’t prove anything.

HAL: Okay, what would?

CATHERINE: Nothing.

You should have trusted me.

Related Characters: Catherine (speaker), Hal (speaker)
Related Symbols: Proof
Page Number: 80-81
Explanation and Analysis:

HAL: There is nothing wrong with you.

CATHERINE: I think I’m like my dad.

HAL: I think you are too.

CATHERINE: I’m…afraid I’m like my dad.

HAL: You’re not him.

CATHERINE: Maybe I will be.

HAL: Maybe. Maybe you’ll be better.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Page Number: 82
Explanation and Analysis:
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Catherine Quotes in Proof

The Proof quotes below are all either spoken by Catherine or refer to Catherine. For each quote, you can also see the other characters and themes related to it (each theme is indicated by its own dot and icon, like this one:
Genius and Mental Instability Theme Icon
).
Act One, Scene 1 Quotes

ROBERT: You see? Even your depression is mathematical. Stop moping and get to work. The kind of potential you have—

CATHERINE: I haven’t done anything good.

ROBERT: You’re young. You’ve got time.

CATHERINE: I do?

ROBERT: Yes.

CATHERINE: By the time you were my age you were famous.

Related Characters: Catherine (speaker), Robert (speaker)
Page Number: 10
Explanation and Analysis:

CATHERINE: You died a week ago […] You’re sitting here. You’re giving me advice. You brought me champagne.

ROBERT: Yes.

CATHERINE: Which means…

ROBERT: For you?

CATHERINE: Yes.

ROBERT: For you, Catherine, my daughter, who I love very much…It could be a bad sign.

Related Characters: Catherine (speaker), Robert (speaker)
Page Number: 13
Explanation and Analysis:

HAL: […] When your dad was younger than both of us, he made major contributions to three fields: game theory, algebraic geometry, and nonlinear operator theory. Most of us never get our heads around one. He basically invented the mathematical techniques for studying rational behavior, and he gave the astrophysicists plenty to work over too. Okay?

CATHERINE: Don’t lecture me.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Page Number: 17
Explanation and Analysis:

HAL: […] “Talking with students helps. So does being outside, eating meals in restaurants, riding buses, all the activities of ‘normal’ life. Most of all Cathy. The years she has lost caring for me […] her refusal to let me be institutionalized—her keeping me at home, caring for me herself, has certainly saved my life. Made writing this possible. Made it possible to imagine doing math again […] I can never repay her.”

Related Characters: Robert (speaker), Hal (speaker), Catherine
Page Number: 23
Explanation and Analysis:
Act One, Scene 2 Quotes

CLAIRE: Did you use that conditioner I bought you?

CATHERINE: No, shit, I forgot.

CLAIRE: It’s my favorite. You’ll love it, Katie. I want you to try it. […] It has jojoba […] It’s something they put in for healthy hair.

CATHERINE: Hair is dead […] It’s dead tissue. You can’t make it healthy.

CLAIRE: It makes my hair feel, look, and smell good. That’s the extent of my information about it. You might like it if you decide to use it.

Related Characters: Catherine (speaker), Claire (speaker)
Page Number: 24-25
Explanation and Analysis:
Act One, Scene 3 Quotes

CATHERINE: […] Later a mutual friend told [Gauss] the brilliant young man was a woman.

He wrote to her: “A taste for the mysteries of numbers is excessively rare, but when a person of the sex which, according to our customs and prejudices, must encounter infinitely more difficulties than men to familiarize herself with these thorny researches, succeeds nevertheless in penetrating the most obscure parts of them, then without a doubt she must have the noblest courage, quite extraordinary talents, and superior genius.”

(Now self-conscious) I memorized it…

Related Characters: Catherine (speaker), Gauss (speaker), Sophie Germain
Page Number: 36
Explanation and Analysis:
Act One, Scene 4 Quotes

CATHERINE: I know you mean well. I’m just not sure what I want to do. I mean to be honest you were right yesterday. I do feel a little confused. I’m tired. It’s been a pretty weird couple of years. I think I’d like to take some time to figure things out.

CLAIRE: You could do that in New York.

CATHERINE: And I could do it here.

CLAIRE: But it would be much easier for me to get you set up in an apartment in New York, and—

CATHERINE: I don’t need an apartment, I’ll stay in the house.

CLAIRE: We’re selling the house.

Related Characters: Catherine (speaker), Claire (speaker)
Page Number: 42-43
Explanation and Analysis:

CLAIRE: Living here with him didn’t do you any good. You said that yourself.

You had so much talent…

CATHERINE: You think I’m like Dad.

CLAIRE: I think you have some of his talent and some of his tendency toward…instability.

Related Characters: Catherine (speaker), Claire (speaker), Robert
Page Number: 45
Explanation and Analysis:
Act Two, Scene 1 Quotes

ROBERT: […] I’m not doing much right now. It does get harder. It’s a stereotype that happens to be true, unfortunately for me—unfortunately for you, for all of us.

CATHERINE: Maybe you’ll get lucky.

ROBERT: Maybe I will. Maybe you’ll pick up where I left off.

CATHERINE: Don’t hold your breath.

ROBERT: Don’t underestimate yourself.

Related Characters: Catherine (speaker), Robert (speaker), Hal
Page Number: 57
Explanation and Analysis:
Act Two, Scene 2 Quotes

CLAIRE: […] You wrote this incredible thing and you didn’t tell anyone?

CATHERINE: I’m telling you both now. After I dropped out of school I had nothing to do. I was depressed, really depressed, but at a certain point I decided, Fuck it, I don’t need them. It’s just math, I can do it on my own. So I kept working here. I worked at night, after Dad had gone to sleep. It was hard but I did it. […]

CLAIRE: Catherine, I’m sorry but I just find this very hard to believe.

Related Characters: Catherine (speaker), Claire (speaker), Robert
Related Symbols: Proof
Page Number: 60-61
Explanation and Analysis:

HAL: I’ll tell them we’ve found something, something potentially major, we’re not sure about the authorship; I’ll sit done with them. We’ll go through the thing carefully […] and figure out exactly what we’ve got. It would only take a couple of days, probably, and then we’d have a lot more information. […]

CATHERINE: You can’t take it …] You don’t waste any time, do you? No hesitation. You can’t wait to show them your brilliant discovery.

HAL: I’m trying to determine what this is.

CATHERINE: I’m telling you what it is.

HAL: You don’t know!

CATHERINE: I wrote it.

Related Characters: Catherine (speaker), Hal (speaker)
Related Symbols: Proof
Page Number: 63
Explanation and Analysis:

HAL: I’m a mathematician […] I know how hard it would be to come up with something like this. I mean it’s impossible. You’d have to be…you’d have to be your dad, basically. Your dad at the peak of his powers.

CATHERINE: I’m a mathematician too.

HAL: Not like your dad.

CATHERINE: Oh, he’s the only one who could have done this?

HAL: The only one I know.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Related Symbols: Proof
Page Number: 64
Explanation and Analysis:
Act Two, Scene 3 Quotes

CLAIRE: […] I probably inherited about one one-thousandth of my father’s ability. It’s enough.

Catherine got more, I’m not sure how much.

Related Characters: Claire (speaker), Catherine, Robert
Page Number: 68
Explanation and Analysis:
Act Two, Scene 4 Quotes

CATHERINE: “[…] In September the students come back and the bookstores are full. Let X equal the month of full bookstores. The number of books approaches infinity as the number of months of cold approaches four. I will never be as cold now as I will in the future. The future of cold is infinite. The future of heat is the future of cold. The bookstores are infinite and so are never full except in September…” […] It’s all right. We’ll go inside.

ROBERT: I’m cold.

CATHERINE: We’ll warm you up.

ROBERT: Don’t leave. Please.

CATHERINE: I won’t. Let’s go inside.

Related Characters: Catherine (speaker), Robert (speaker)
Page Number: 74
Explanation and Analysis:
Act Two, Scene 5 Quotes

HAL: […] Your dad dated everything. Even his most incoherent entries he dated. There are no dates in this.

CATHERINE: The handwriting—

HAL: —looks like your dad’s. Parents and children sometimes have similar handwriting, especially if they’ve spent a lot of time together.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Related Symbols: Proof
Page Number: 80
Explanation and Analysis:

HAL: Come on, Catherine. I’m trying to correct things.

CATHERINE: You can’t. Do you hear me?

You think you’ve figured something out? You run over here so pleased with yourself because you changed your mind. Now you’re certain. You’re so…sloppy. You don’t know anything. The book, the math, the dates, the writing, all that stuff you decided with your buddies, it’s just evidence. It doesn’t finish the job. It doesn’t prove anything.

HAL: Okay, what would?

CATHERINE: Nothing.

You should have trusted me.

Related Characters: Catherine (speaker), Hal (speaker)
Related Symbols: Proof
Page Number: 80-81
Explanation and Analysis:

HAL: There is nothing wrong with you.

CATHERINE: I think I’m like my dad.

HAL: I think you are too.

CATHERINE: I’m…afraid I’m like my dad.

HAL: You’re not him.

CATHERINE: Maybe I will be.

HAL: Maybe. Maybe you’ll be better.

Related Characters: Catherine (speaker), Hal (speaker), Robert
Page Number: 82
Explanation and Analysis: