Maine's cornucopia of arts; Jack Jones; swing-dancing in Boston

If you want to find out what makes a state's residents tick, visit its arts festival. The kind of entertainment you'll see there is a real barometer of the quality of the people's thought and the values they cherish.

At the eighth annual Maine Festival, held recently at Bowdoin College in Brunswick, organizers chose the 600 performers on the basis of merit, not ''Maineness.'' But certain threads woven through the festival showed that all came from the same rocky soil and wind-swept seacoast.

One thing that stood out was their affectionate reverence for traditional arts. The best music came from the folk arts area. Poker-faced senior fiddlers made their instruments smoke and sing, with that relaxed precision that comes from playing together for years. One of the most popular (and youngest) groups was the ''Sweet Grass Cloggers,'' who are enthusiastically reviving the art of clog-dancing.

The crafts, too, leaned toward the indigenous - chain-saw sculptures and demonstrations of ploys (buckwheat pancakes) and boat building. The Northeast Archives of Folklore and Oral History collected Maine stories from passers-by.

But Maine is far from just rooted in the past, as other exhibits showed. One of the most delightful ideas was a specially commissioned dance tent - an inflatable pink and white balloonish structure that moved and swayed in the wind along with the dancers. Gayle Fraas and Duncan Slade have updated quilting techniques by dyeing fabric in vivid colors, then stitching and quilting it into a futuristic, faintly Middle Eastern ''painting.''

There was a bucketload of things to see and hear. Jazz and rock groups, a dozen dance troupes, film and video offerings, street performers - all amiably vied for attention.

The link I sensed in all this abundance of talent was a seriousness of purpose. Except for some clowning and exuberant stiltwalkers, there was little whimsy. The ideas were usually provoking - ''Testament: A Rock and Roll Mystery Play'' dealt with the mysterious death of a career soldier - even if the execution was not always technically perfect.

I came away feeling that ''Maineiacs'' both revere their traditions and eagerly seek the best of what's new. Forged perhaps out of the isolation and hard winters, everything had the stamp of careful craftsmanship.