Why is Viggo Mortensen's portrayal of Aragorn in The Lord of the Rings trilogy so good? It could be his immersion in J. R. R. Tolkien's original novels: He can speak knowledgeably on why Aragorn carries a bow, although it's not directly mentioned in the original text. Or it could be his complete dedication to the role: During filming, Mortensen went everywhere with his sword, even to restaurants. Or it could be his overall intelligence: When he first read The Lord of the Rings (on the plane down to New Zealand, after he was brought in as a last-minute replacement), he was struck by the echoes of Beowulf and ancient Icelandic sagas. Once he had landed, he bought a pile of the books Tolkien himself had used as sources. 'I made it a classroom in mythology and literature,' he says - and he turned Aragorn into an uncommon film hero, one with genuine mythic resonances across the centuries.

Viggo (pronounced Vee-go) Mortensen, 44, has done enough to make everyone else in the Western Hemisphere feel like a slacker. He's acted in nearly forty films, starting with Witness and including particularly fine performances as a damaged Vietnam vet in The Indian Runner and a hippie blouse salesman in A Walk on the Moon. He paints and take photographs (his latest works are collected in a book called 45301), writes poetry in three languages and runs a small publishing house, Perceval Press.

Mortensen's father is Danish, his mother American, so, naturally, he spent a lot of his childhood in Argentina. As a kid he was happy to spend endless hours by himself - a preference that he still has as an adult. Mortensen was once married to Exene Cervenka of the legendary punk band X; their son, Henry, now fifteen, is the one who encouraged Mortensen to take the role of Aragorn. In Tolkien's book, the hobbit Frodo is the central character, but in Peter Jackson's films, Mortensen's regal charisma steals the limelight, making him the subject of Oscar talk.

When we speak, Mortensen is in the kitchen of his home in Venice, California, drinking strong, green Argentinean maté tea, brewed from twigs, and cooking himself dinner (Korean dumplings). Our conversation ranges from the career of painter Gerhard Richter to the history of the Danish language to modern movie marketing ('You're usually in the business of talking people into seeing something they're not going to remember for very long.') He's heading off to London for some final reshoots on The Lord of the Rings: The Return of the King. Although he's proud of the Middle Earth movies, he's clearly looking forward to being done with them so he can devote more time to his art and his publishing house.

Mortensen has one other movie in the can: Hidalgo, due out next March. He plays nineteenth century cowboy Frank T. Hopkins, the first American to ride in the Ocean of Fire, a 3,000-mile horse race in the Arabian desert. Mortensen was particularly keen on the film, because he felt it didn't feature the usual jingoist plot in which an American goes abroad and solves the world's problems. At the end of a day of filming in the desert, the crew would pack up for the two-hour drive back to the hotel. Mortensen, however, would stay behind and sleep in the sand dunes, the rare Hollywood actor who is happiest when alone with a book, his thoughts and the stars in the sky.