Errol Morris, the great Oscar-winning documentarian, has also had a brilliant career in advertising.

He has shot over 1,000 commercials, including campaigns for Apple, American Express, Nike, IBM, PBS, Target, General Motors, Miller High Life and Cisco. His Apple “Switchers” campaign through TBWA\Chiat\Day and the “High Life Man” spots via Wieden + Kennedy are both legendary ad series. And in 2001, his “Photobooth” spot for PBS, via Fallon Minneapolis, won the Emmy for Best Commercial. (See a vast selection of his ads over on his website.)

Morris, 69, whose 11 films include the classic documentaries Gates of Heaven, The Thin Blue Line and the Academy Award-winning The Fog of War, continues to make films. His latest is The B-Side: Elsa Dorfman’s Portrait Photography. He also filmed a miniseries for Netflix called Wormwood, starring Peter Sarsgaard, about the true story of Cold War-era military scientist Frank Olson. That series, which debuted in mid-December, blends long-form documentary interviews with dramatic reconstructions of some scenes.

Morris isn’t done with ads, either. He just signed with Biscuit Filmworks for commercial representation in the U.S. and U.K. (He was previously repped by Moxie Pictures.) And he hopes to bring his signature style to many more ad campaigns.

Adweek spoke with Morris by phone this week about his approach to ads, his way of working on set, how the Apple and High Life campaigns came about, and that time he interviewed Donald Trump about Citizen Kane.

Congrats on the deal with Biscuit Filmworks. What attracted you to Biscuit? Do you have any history with them?

Thank you. I really don’t have a history with them. But yes, I do like them a lot. I wouldn’t have joined the company if I didn’t. I like Shawn Lacy a lot. Why do you join a company? Because you believe they can help you get work. It sounds a little bit prosaic, the way I’m putting it. But in truth, that is a main motivation.

You’ve said you like making commercials, that you find it challenging. What’s challenging about it?

Well, it’s filmmaking, properly considered. I once described commercials as America’s haiku. I don’t know if that’s true or not, but you’re making little films, in essence. And it’s as challenging as any other kind of filmmaking. The fact that it’s all compressed into a very confined piece of temporal real estate makes it harder, not easier. I sometimes say brevity is the soul of concision. Or maybe concision is the soul of brevity. I’m not sure how I would order it. But it’s the goal of finding ways to tell a story. Really good advertising is about telling stories, about creating ideas for a brand. And as such, it’s a difficult and daunting enterprise.

I like to think I’m good at it, also. It’s something I enjoy. I enjoy thinking about how to put across an idea about branding or marketing. I’ve been lucky because I’ve had the opportunity over the years to do a lot of campaigns that are about defining a brand, or redefining a brand. And that’s what I like to do most, because it’s an intellectual activity. “How can I best express this?” “How can I make people think about something in a different way?” Is that so different than making a film? It is and it isn’t.

A lot of creative people talk about how working inside a box, with limitations and constraints, can make the creative process easier. I suppose a commercial is just a smaller box.

It’s still an enormous challenge to do well. I’ve never found them easy. It often is not clear what to do. It’s a form of thinking, if you like. I’ve also been lucky that I’ve done all kinds of commercials. It strikes me as ironic. I’m known, I suppose, for interviewing people, among other things. But that wasn’t always the case. Around the time of The Thin Blue Line, which is now close to 30 years old, people would use me for visual storytelling, because of the re-enactments in The Thin Blue Line. And so the commercials I would get were basically little dramas, including all the work I did for Miller High Life, which in the end, I think, was well over 100 commercials. I think things have changed somewhat, but in those days, you could be hired to do a lot of work for one client. So, I ended up doing a lot of work for Citibank. And Miller, of course.