Dave Van Ronk glanced at the song list taped to his guitar. "I always write this, then I change it," he said. If he bothered to write down all the songs in his head, the list would reach down the side of his guitar and out into the street.

Van Ronk is a troubadour in the finest sense-he is a walking storehouse of songs, stories and musical memorabilia. Last night at the Cellar Door, he sang everything from ragtime to gospel to vaudeville tunes.

Sitting there, picking out a bluesy melody and growling a bawdy chorus beneath a shaggy gray beard, he looked like a cross between an old walrus and a Delta blues man. He sang with a wit and feeling that sprang from an honest affection for the songs and the joy of singing. He belted out lusty versions of "God Bless the Child" and "Jesus Met the Woman at the Well," then switched to a snappy rendition of Scott Joplin's "Maple Leaf Rag."

He and his songs are old acquaintances, and he took a few liberties with them, changing a word or two, adding gravel-voiced accetns and throwing in a joke between verses to keep things fresh.

Between songs, the crowd yelled out their favorites and Van Ronk responded, "Let's compromise. I'll do exactly what I please." The way he performed, he could have played what he pleased for as long as he pleased, and no one would have minded a bit.