September 1982. After years of owning guitars here and there, just messing around really, learning a few basic chords on my own, I got myself a first-rate instrument and vowed to find the same quality in a teacher. It was a good 30th birthday vow. This time would be different, and I was going to learn to play instead of just talking about it, maybe play well enough to "sit in" with some pros without embarrassing myself.

The teacher at the Music Barn in Greensboro was a fellow named Ken Dagenet, a curly-headed fellow with a dry sense of humor, a tremendously gifted player in his own right who had developed through many years and hundreds of students a teaching method that would take the student in an orderly fashion through the basics, with just enough flash to keep him or her interested and practicing before going to the next level.

Many years after they'd given up lessons for one reason or another, Ken's students still held on to their spiral notebooks, to which they would periodically return. And in every one, the first page included the notes for the song Ken always started with for new students. He thought it was easy enough for beginners to grasp, but interesting enough to challenge them. It did require some movement up and down the neck and had some nice "licks" in it and was a tune most of them knew, even if they didn't know why they knew it.

The melody was simple, but memorable, one of those songs they could sing, years after they'd forgotten how to play it. And if they heard others playing it, at parties or wherever, they'd ask, "Did you take lessons from Ken Dagenet?" It was Ken's way of passing something on, beyond just notes on a page.

The song was "Freight Train." At different times over many decades, it may have been credited to other writers, or fallen under the label of "traditional," which means that its origins were uncertain.

But they weren't. A 12-year-old girl named Elizabeth Cotten from the countryside near Chapel Hill wrote the song shortly after she learned to play a guitar, upside down, for she was left-handed. Then, the story goes, she married at 15 and put the guitar away for over 40 years. As The News & Observer's Barbara Barrett reported Sunday in a splendid recounting of that story, Cotten wound up working as a housekeeper for the Seeger family outside Washington. One member of the family was Mike Seeger, a performer of old-time music and folklorist (and the half-brother of the legendary Pete Seeger). He heard Cotten playing "Freight Train" when he was a kid and later arranged for a recording contract and toured with her himself. At the time she was "recognized," she was well into her 60s.

She did get credit for the song (and won a Grammy award along the way), which became an American classic, and the Martin guitar company even put out a limited edition instrument in her honor. But the best accolade of all may be the inclusion, this year, of her song in the national recording registry of the Library of Congress, deemed one of the most important songs in history.

Mike Seeger sees an even larger significance, as Barrett reported. "Every time," he said, "if I'm in D.C. and passing a bus stop and seeing brown-skinned women there, I say, 'I wonder what they can do.' The station you find yourself in, in life, doesn't always reflect your potential."

Which in Seeger's view makes Cotten's story significant in American history. That's not a stretch, and to be sure, she earned her good fortune but was helped by an honorable man in Seeger, who knew that people would want to see her perform and saw to it that they did. (Cotten died in 1987. She was in her 90s.)

On this Independence Day eve, Cotten's is a spectacularly American story, and her song carries her legend on, as does Woody Guthrie's "This Land Is Your Land" for him, as certain songs do for a relatively small number of others.

A real legacy survives forever, through story or voice ... or strings. Ken Dagenet died in 2006, but by then he'd done his part, in the key of G, to teach people a little history and a little biography about Libba Cotten, and a very good song, too. Thanks, Kenny. Tomorrow, perhaps, some of the old students will get out the notebooks and pass it on again.