The French have an expression for this. It's "Je ne sais quoi." We adopt this expression in English because it has more of an aura of mystique around it than the literal translation, "I don't know what." Brief Encounter has "je ne sais quoi." The story is very plain, really: a woman has a chance meeting with a man at a train station, and that, in turn, develops into an affair, if not physically then emotionally. She is ridden with guilt, and her husband remains cheerily unaware. How many movies have a kind of premise like this? Most that are this simple disguise the fact by mashing in things around the edges: subplots, whacky sidekicks, snappy one liners, whatever. Brief Encounter is bereft of distractions; the essence of the story is left to sink or swim on its own.

It swims. I have no idea why. I cannot sit back and tell you precisely what director David Lean does that makes this overused material so riveting, nor can I tell you exactly what stars Celia Johnson and Trevor Howard accomplish to embody characters that enter into an illicit relationship while remaining purely sympathetic characters. A lesser director or a lesser cast, and this movie would have been long forgotten. As it is, this film is considered one of David Lean's finest accomplishments from his early period. It is greatly satisfying, because it tackles tough subject matter and raises difficult questions about why good people are drawn into doing bad things. It makes a powerful statement about the importance of doing the right thing while simultaneously showing how difficult it can be to have the strength to do it -- and, at times, to figure out why "the right thing" is the right thing after all. We can hardly blame the characters for their confusion, so vividly are their emotional states portrayed on the screen in a way we can identify with even if we've never been in their particular circumstances.

Lean, of course, is better remembered for such sweeping epics as The Bridge On the River Kwai, Lawrence of Arabia, and Dr. Zhivago. But while these films made him a legend, this one small wonderful little gem, made eleven years before Kwai, had already established his greatness.