Laura Esping, left, plays Ruth Bader Ginsburg and Patty Mathews plays Sandra Day O’Connor in “Sisters in Law” at Six Points Theater. (Sarah Whiting/The Minnesota Star Tribune)

Two trailblazing Supremes did not sing but they worked in harmony to help reshape America.

Sandra Day O'Connor and Ruth Bader Ginsburg were the first two female justices on the U.S. Supreme Court. That they became close friends shows that birth and background do not prefigure destiny.

Hailing from rural Arizona, O'Connor grew up on a ranch and cleaved to conservative values. Ginsburg was a proud liberal from Brooklyn — the same New York City borough as legendary rapper Notorious B.I.G., hence her nickname, "Notorious RBG."

In the late 20th century, the two women worked to empower women and also opened the door to an institution that had been male-dominated for centuries. Their unlikely friendship is the subject of Linda Hirshman's bestselling book "Sisters in Law," which was adapted for the stage by Jonathan Shapiro.

Patty Mathews, right, plays Sandra Day O’Connor and Laura Esping is Ruth Bader Ginsburg in Six Points Theater’s “Sisters in Law.” The play is adapted from Linda Hirshman’s joint biography of the first and second women to serve on the U.S. Supreme Court. (Sarah Whiting/The Minnesota Star Tribune)

The play opens Saturday in St. Paul's Six Points Theater, just days after Supreme Court Justice Amy Coney Barrett's controversial visit to the University of Minnesota. (Barrett replaced Ginsburg.)

Four of the six women to ever serve on the nation's highest court have been three-named wonders, with Ketanji Brown Jackson being the latest justice. Outliers are Justices Sonia Sotomayor and Elena Kagan. The question arises, do women have to have three names to be on the Supreme Court?

"Gosh, it does seem like it when you put it that way," said Patty Mathews, who plays O'Connor in "Sisters."

"Of course, they would argue for the freedom of any names," said Laura Esping, who plays Ginsburg.

We asked these two performers to share some of the things they learned about O'Connor and Ginsburg as they take their deep dives. Their answers have been edited for clarity and concision.

In “Sisters in Law,” Ruth Bader Ginsburg (Laura Esping) watches the news that Sandra Day O’Connor will be nominated as the first female U.S. Supreme Court justice by President Ronald Reagan. (Sarah Whiting/The Minnesota Star Tribune)

Q: How much do you identify with the two justices?
Mathews: Sandra is a breast cancer survivor, and I am, as well. When she got her diagnosis, she was like, 'Well, let's see, I might be able to fit in some treatments in December during our break because I'm too busy.' And the doctors were like, 'No, you're going to have treatment now because we can't wait for months.' She wanted to keep her life as normal as possible. She didn't want her illness to define her or to be treated like a sick or weak person. That was me, too. We both got through and were able to go to work and keep going. I was proud of the way I handled it and to hear that somebody who is this great person handled it the same way. She's a kindred spirit.

Esping: [O'Connor] probably inspired Ruth for she, too, had cancer — pancreatic. But then she starts working out at age 70 — going to the gym, lifting weights, aerobics. She becomes this sensation and is working out on late-night TV. Totally inspiring.

Justice Sandra Day O’Connor (Patty Mathews) was known to be a fine golfer. She is said to have practiced for two years on a driving range before ever playing on a course. (Sarah Whiting/The Minnesota Star Tribune)

Q: What's most surprising to know about these justices?
Esping: That they were, are so human. RBG married Marty Ginsburg and he appreciates her brilliance. Her mother-in-law got her earplugs as a wedding present and told her that one of the secrets of a happy marriage was to be a little deaf sometimes. Sometimes you've got to let things roll off your back. She used that advice on the court, especially when dealing with all those men. Marty got cancer when they were in law school together and she took care of him and their baby while going to class. She's getting like two hours of sleep a night.

Q: It wasn't an easy journey for either one of them and they had to jump discriminatory hurdles.

Esping: RBG as a Jewish person and, also, as a woman. When she was a student, she was not allowed to go into the law library to study during school.

Mathews: Both of them graduated at the top of their class and could not get a law job because none of the firms had women lawyers at that time.

Q: That must have informed their values.
Esping: All of this helped shape [Ginsburg's] sense of justice. She had an urgency and was smart about advancing her values.

Mathews: Sandra is more like one step at a time, brick by brick. They agreed on the solution, and even the direction, but not the pace. People don't think that Sandra Day O'Connor is still alive. She has dementia and lives in Arizona. But she's still very much with us.

Q: Did they have regrets?
Esping: Besides for the lack of passage of the Equal Rights Amendment? There is a moment toward the end of the play where Sandra says, "I feel like we've failed because women's rights are a mess." No matter how much they accomplished, they both felt that they just didn't do enough.

Mathews: No matter how much they did, they never feel like they got far enough.

Q: What are your characters' journeys in the play?
Esping: We start from 1973, the year of Roe v. Wade, and go to 2018. So, we age from our late 30s all the way to our 80s. And we're aging as we continue to have these discussions.

Mathews: It's a whole life. You see their struggles, their humanity and brilliance.

Esping: Now, if we could just have a little bit of that brilliance rub off on us. [Laughs]

'Sisters in Law'
Who: By Jonathan Shapiro. Directed by Laura Stearns for Six Points Theater.
Where: Highland Park Community Center Theater, 1978 Ford Pkwy., St. Paul.
When: 1 p.m. Tue., 7:30 p.m. Wed.-Thu., 8 p.m. Sat., 1 & 7 p.m. Sun. Ends Nov. 5.
Tickets: $26-$40. 651-647-4315. sixpointstheater.org.