"Good Will Hunting" proves, if nothing else, that actors Matt Damon and Ben Affleck would have a career in the movie business even if they couldn't act. (For the record, though, they're both very good performers.)

The two longtime friends actually wrote a story featuring the main character in 1992 and continued to work on a corresponding movie script for years afterward. That work paid off, resulting in a rich comedy/drama that's surprisingly mature, coming from such young writers — although it is marred by extremely vulgar and profane material.

The movie also benefits from understated, low-key direction by Gus Van Sant ("To Die For"), which allows the stars to develop character relationships nicely.

Damon stars as Will Hunting, an emotionally immature 20-something living on the south side of Boston. Though he's constantly in trouble and is working a dead-end job as a janitor at the Massachusetts Institute of Technology, Will is hiding his true talents — he's a gifted natural mathematician who can easily solve problems that stump even the experts.

His secret is discovered by Professor Lambeau (Stellan Skarsgard, from "Breaking the Waves" and "Amistad"), who helps bail Will out of jail (the result of a nasty playground fight). He also forces him to undergo counseling. Will verbally abuses several therapists until he meets broken-down professor Sean McGuire (Robin Williams).

Under Sean's tutelage, Will begins to confront his past and starts living for the future — with additional help from Skylar (Minnie Driver), a student at nearby Harvard University. That's not what Lambeau is looking for, though, and ultimately he and Sean struggle to control Will's destiny.

Damon and Affleck show a wisdom beyond their years with some of the dialogue, which is alternately poignant and humorous. And Van Sant allows his actors to give very natural performances, especially Damon and Williams, who are both wonderful.

"Good Will Hunting" is rated R for almost constant profanity, some very vulgar jokes and references, violence, sex, glimpses of nude paintings and racial epithets.