Early on in the American Roots/Roots Music set (Sunday on the Plaza stage), performer Darryl Purpose brought up the question that had plagued him while he was deciding what to play for his part of the show: what is Folk music, anyway?

Each of the performers gathered there-Purpose, Alistair Moock, Ellis Paul and Utah Phillips-tried to answer this question through story and song.

It was Utah Phillips who perhaps gave the best answer, saying, “When a song starts becoming a folk song is when it changes.” In other words, when people take the song and adapt it to different purposes and situations, working it into the fabric of their culture.

The artists illustrated this idea in their performances. Each of them had a distinct style and voice, a different way of approaching the music, yet each drew on the same rich tradition to express what was personally important to them about folk music.

Moock was harder-edged than the others, showing a Blues and Rockabilly influence. Purpose played in a traditional fingerpicking style; his songs were full of warmth and laughter. Ellis Paul was the one real let down of the show; he is simply a pompous sounding singer, and his choices lacked originality. Paul is to the Folk genre as Kenny G. is to Jazz; he sells schlock as art, he’s a sheep in wolf’s clothing.

All four shared their experiences as musicians and songwriters, telling stories and creating a sense of an artistically vital, historically informed and socially aware music form.

They performed a mix of covers and original songs, many of which (like Purpose’s “Singer-Songwriter Heaven”) were tributes to their influences. Woody Guthrie (the model of the working-class spokesman folksinger) was represented in two covers, one by Moock and the other by Paul.

What became clear through the set was the fact that so much of the meaning of folk music is in its history, and its history is our history. Folk music is one of our most important cultural memories, a long memory, and as Utah Phillips put it, “the long memory is the most radical idea in America.”

He should know. To many, Phillips is himself a folk legend, a living extension of that “long memory.” During the show, Phillips told stories of folk heroes; not just musicians, but activists and ordinary people who refused to stand down in the face of injustice. In a booming voice, he sang humorous anthems of the labor movement.

Overall, it was an entertaining and educational affair. The performers were laid-back and conversational, and most importantly there was a real sense of community, not just on-stage but between the performers and the audience. Community is, after all, central to the meaning of folk music which, most simply defined, is just music for folks. That is to say, music for all of us.