When director Matthew Brown was ready to cast "Freud's Last Session," a film that imagines a conversation between Sigmund Freud and C.S. Lewis, it was Anthony Hopkins he thought of first to play the father of psychoanalysis.

"Anthony Hopkins, that was always the No. 1 you could ever dream of getting," Brown says. "I wasn't surprised when he said no at first. I think he was in the midst of (the film) 'The Father.'"

But Brown didn't give up on the dream. He worked on the script that he co-wrote with Mark St. Germain, who had written the stage play upon which the movie was adapted, and found a way to get it back in front of Hopkins once more.

"When he said yes, it was basically 'game on' at that point," Brown says.

British actor Matthew Goode, known for his work on television in "Downton Abbey" and "The Good Wife," and in film for "The Imitation Game" and "Watchmen," was cast as C.S. Lewis.

"Matthew, as much as he loved me or the material, I think he was just as excited to get the chance to work with Anthony Hopkins, who was a childhood hero to him," Brown says. "That brings its own challenges, because we're all in awe. He's the great one, and we're all intimidated ...

"Somebody asked, 'What's it like to direct Tony Hopkins?' I was like, You don't even get a chance to think about it because he engages with you so fast. And he's so excited about the work that you just fall right in and everyone's just working.

"He brings everybody's A-game out, and that's something you learn when you're working on a film like that. What that actually looks like."

In "Freud's Last Session," which opened Dec. 22, Freud and Lewis meet in England in September 1939 as Germany invades Poland and the world is fraught with fear. Freud, an atheist, who is just weeks away from dying from cancer, wants to talk with Lewis, a former nonbeliever, about his belief in God.

Their conversation, interspersed with recollections of their earlier lives, Freud's struggle with his daughter Anna, and Lewis's PTSD from World War I, shifts from sharp realism to dream-like reveries, as the two men debate their beliefs with each other.

Q: How did you come to the story? Through Mark St. Germain's play or Armand Nicholi's book ("The Question of God: C.S. Lewis and Sigmund Freud Debate God, Love, Sex, and the Meaning of Life") that inspired the play?

A: I should also say my father is a psychiatrist, so there's that. It came to me as a first draft of a screenplay that was based on the play that was based on the work by Nicholi, which was a class up at Harvard that ran for 35 years. It was a course that looked at atheism through the eyes of Freud.

And then about halfway through, Armand wanted to have a counterpoint, and he chose C.S. Lewis to represent. Because Lewis had his own journey from atheism to finding his faith.

Then Mark wrote a beautiful play, that was incredible, but it was all set in one room, which is a challenge for a film.

Q: So what needed to happen to expand it beyond the room to make it work better as a feature?

A: It started with the arc of the conversation, you know, the intellectual conversation. But then you also have these two incredibly interesting people, both just brilliant and creative. We understand that about C.S. Lewis and Freud, but they were also incredibly flawed human beings, which is fascinating. They were so complicated.

So that needed to be investigated. And I felt that in order to really feel that as an audience member, that we had a grasp on it, that to get outside the room and into some of their lives was going to be essential.

Like PTSD for Lewis. You can say he has PTSD, but until you've been in those trenches ... I think it makes a big difference and gives some weight to the characters beyond just an intellectual conversation. And it also opens it up visually. I'm excited because I think every time we leave the room, we're moving that personal inner life story forward.

Q: It's interesting that Anthony Hopkins played C.S. Lewis 30 years ago in 'Shadowlands.' What was it like to have him, with that experience, playing Freud opposite Matthew Goode as C.S. Lewis here?

A: That was interesting. Matthew did a little homage to him and wore the same sweater and suit that (Hopkins) wore in 'Shadowlands.' But beyond that, he had a chance to talk to him, as did I, about his own take on Lewis. And so we had some insights there.

He kind of said just do your own thing, make your own way here. This was a dream film, you know, we don't know if it actually happened or didn't happen. So it gave us all a bit of freedom.

I think Hopkins also really felt like, Let's lean into the dream aspects as well. So he was on board for that. He's incredibly creatively generous, and just, it was a real joy. It's not one of those things where you're just sugarcoating it, or saying, 'Oh, he's really unbelievable.' I mean, people don't know he's a world-class musician and painter, but that whole last waltz at the end of the film was something that he wrote.

Q: You mentioned the excitement of spending days filming the two of them in the set of Freud's office. As the director, what was that like?

A: It was a challenge because we were doing, at times, seven pages a day. And, I mean, Hopkins is older. (He turned 86 on Dec. 31.) And he's not using an earpiece, he's not using big cue cards. He did so much preparation for this film.

Basically, we needed to get a really safe space on that stage. We managed to do it in a linear form. We weren't jumping all around, so we could take it from the beginning to the end, for the most part, which was a big help. We were all kind of emotionally tracking where we were together.

I think it's a tribute to Matthew and his kindness, and Tony's kindness, really. That's what it comes down to, just respect and trust.

Q: The story takes place more than 80 years ago. How do you imagine audiences will connect to 'Freud's Last Session' and find it relevant to their lives today?

A: I mean, I guess the question of our time is science versus religion. But the culture that was happening in 1939, it was one of fear. It was tyranny and fascism on the rise. It was a scary time. You don't have to be too astute to catch the parallels between the two. It feels like this could be happening today as much as it was happening then.

I started working on this about five, six years ago, and at that time I thought, wow, this feels timely. I mean, things have gotten to the point where you can't say anything anymore because you're afraid you're going to get canceled from one side or canceled from the other side. And that's a really scary thing.

You hope that when people come out of this movie, maybe they'll turn to the person next to them and be able to have a conversation and do it with respect. It was really nice, even if it is somewhat fictional to have C.S. Lewis and Sigmund Freud, two of the greatest minds of the 20th century, actually wanting to do it because they're intellectually curious.