"There's comfort in melancholy..." This is a line from one of Joni Mitchell's songs, and a melancholy thoughtfulness runs through most of her work. So it seems only logical that Joni Mitchell would evolve from Canadian born folk musician to blues-jazz singer extraordinaire. And those fans who were fortunate to be part of the sold out show at the County Bowl yesterday followed her progress through that evolution as she ran the gamut of her many talents.

The concert program ignored chronology, as Joni weaved a pattern of folk, rock, blues, and jazz which delighted her audience.

The Persuasions, "kings of a capella," opened the show. Their now classic sound, which comes from the late '50s and early '60s, added another dimension to the afternoon. In the scorching heat, they danced and cavorted, offering everything from "Sha-na-na" to "The Lords Prayer." They sang of chain gangs, Lowenbrau, Tom Dooley, Sunday Mornings. Their energetic opening lasted an hour. During this time cameras were set up and paraphernalia arranged for taping the concert for television. As the afternoon went on, the distractions of the taping intruded somewhat on the concert, and as Joni sang and moved on and off stage, she was obviously blocking in a pre-arranged fashion, and some of the spontaneity of the performer-audience relationship was lost.

But it would have taken a great deal more than minor distractions to cool the ardor of her fans. She was obviously adored by her audience, from the familiar strains of her opening "parking lot" song through hard rock, not-so hard rock, rock-jazz fusion magnificent blues, talking poetry, folk, and even a hymn.

Joni is a top notch guitarist herself, but this time she had the backing of some superb musicians. Pat Metheny and Jaco Pastorius provided dynamite guitar and bass work, both with Joni and solo. The entire band - piano, sax, drums, guitars - really rocked when required and updated the Joni Mitchell sound on such songs as "Rockin' and Rollin'" and a rousing, rocking "Raised on Robbery" that had the audience dancing and shouting.

Yet, the essence of Joni Mitchell came through time after time, as she told her talking tales of the woes of modern America and modern Americans, such as "Edith and the Kingpin."

Her poetic imagery glowed as she sang of "snow like bolts of lace" and life "between the forceps and the stone..." These were the words of the familiar Joni Mitchell and her melancholy musical lectures on life.

But what of the new Joni Mitchell sound - the inspired blues, the jazz harmonics that have come from her friendship and professional alliance with the late Charles Mingus? It was all there, and Joni's rich, versatile voice sang a blues about Beale Street that put her right up there with Lena Horne and other jazz singers who have been able to play their voices like the warm, rich instruments of the jazz coterie.

Another tribute to Mingus was "God Must Be a Boogie Man," another from her latest album which was inspired by Mingus.

Joni sang it all - the soft, the hard, the upbeat, the sad. She was philosopher, poet, but most of all, musician. The concert began about 4:30. After three encores, the fans reluctantly filled out of the bowl into the darkness about 8 o'clock. It had been a musical highlight of the summer of '79.