Which is, of course, the perfect reason to make great movies. A single performance on stage is ephemeral, but films can still be watched 80 years after they are created. Hoffman would never say that out loud — it would sound too grand, too self-important, too movie-starish. Still, he knows he will not be remembered for his real-life persona but rather for the characters he has chosen to embody. In “Doubt,” for instance, which was originally a play, he is a Catholic priest who may or may not have been inappropriate with a young male student. He is suspected and accused by the principal of the parish school, a nun named Sister Aloysius, played by Meryl Streep. “If I asked 10 people on the subway who I should cast for the older nun, they’d all say Meryl,” Shanley told me. “But I didn’t know what Phil would do with the part of Father Flynn, and that intrigued me. I did know that he would make Meryl sweat, that she would be up against someone of equal intelligence. Meryl is a street fighter, and she schemes as an actress — she wants to win the scene. Phil won’t play that way. He won’t engage. Before their big confrontation scene, Meryl would be muttering ‘I’m going to kick his butt’ for the entire crew to hear. She’d look at him and say, ‘I know you did it.’ And Phil would just laugh and say, ‘Meryl’s always trying to get in my head.’ ”

As usual Hoffman struggled with the character. “On every film, you’ll have nights where you wake up at 2 in the morning and think, I’m awful in this,” he recalled. “You see how delicate it is — a little movement to the right or the left, and you’re hopelessly hokey.” The film revolves around the question of the priest’s culpability, but that is not what mattered to Hoffman. Hoffman plays the priest as a reformer, a man interested in a more philosophical and tolerant approach to religion. Shanley had given Hoffman a “back story” on Father Flynn, who is based, in part, on a teacher who had a profound impact on Shanley as a boy, but Hoffman added his own interpretation. “I did research by, among other things, going to church. As a kid, I was confirmed and I went to church, but I was bored. Now, I feel the opposite: A good sermon is just like theater. It combines the political scene and the Scriptures, and I thought, Hey, I could do it like that. It’s like a teacher getting up and saying, This is the school I come from.”

Since playing the role, Hoffman has been asked repeatedly if Flynn “did it.” He won’t answer. “I wouldn’t ever say whether the priest is innocent or guilty because I saw ‘Doubt’ as being about something larger,” Hoffman said. “What’s so essential about this movie is our desire to be certain about something and say, This is what I believe is right, wrong, black, white. That’s it. To feel confident that you can wake up and live your day and be proud instead of living in what’s really true, which is the whole mess that the world is. The world is hard, and John is saying that being a human on this earth is a complicated, messy thing.” Hoffman paused again. “And I, personally, am uncomfortable with that messiness, just as I acknowledge its absolute necessity. I find the need to play a part like Father Flynn inescapable, and I only want to do things I’m that passionate about. I know there are actors out there that present themselves as cool cats, but you better take your cool-cat suit off if you want to act. You can’t otherwise.”

As he said this, Hoffman sounded more melancholy than strident. He looked up at the stage where the actors were reassembling, about to run through the entire first act. “We’re hitting the moments too much,” Hoffman said to no one in particular. What he seemed to mean is that the characterizations had little individuality, that the actors were spending too much time polishing the shiny surface of the play instead of exploring its nuances. “They have to get back to the simple act of doing something,” Hoffman said patiently. “With any character, you have to bring it back to the normal.”

But, as the director, Hoffman could only inspire them — he couldn’t jump onstage and play all the parts himself. Which may have been a relief. “During ‘Doubt,’ Phil seemed to be in a lot of pain,” Shanley remembered. “He’d smoke cigarette after cigarette and stare out the window. I was afraid to say anything to him. And now when we talk about the movie, he says how much fun he had. I’d say, ‘You looked like you were in hell.’ Phil just shrugs and sort of jokes: ‘Hell? That’s where I live.’ ”

Image Phillips Seymour Hoffman as Father Flynn in his new movie, "Doubt," shown here with Amy Adams as Sister James. Credit... Andrew Schwartz/Miramax Film Corporation

“IT WAS PRETTY GOOD LAST NIGHT,” Hoffman said over lunch the next day at a hotel called One Aldwych, which was near the theater. “We were there until 11:30. I had to show tough support to the cast. I can’t do it for them, but I know how it goes: you open the play, and you’ll have a week that’s weird. And then you have a performance that’s really strong, and you’ll try to find that performance again, as if you’ve never done it before. Finally, you find it again, and you’re on and off for a little while, and then you reach a stretch for a couple of weeks where — wow! — you know how to do the play! And then you become stiff again. And so on. But I can’t tell them all that. They have to figure that out on their own. If I’m on them all the time, it’s never going to be theirs.”