One of the great lines of the year tumbled out of the film Glengarry Glen Ross as Ricky Roma was peddling real estate. Played by Al Pacino, the spidery Roma looked deep into the eyes of a diffident client and said that everyone worries about the past and the future. But no one lives for the moment. You can't say that about John Martyn, whose mysterious career is full of passionate moments.

A 45-year-old native of Glasgow, Scotland, Martyn has been toiling in relative obscurity despite a career that covered 20 albums. Martyn's nocturnally slurred vocals sound like a hybrid of John Hiatt and bluesy Van Morrison. He was extremely tight with the similarly moody British singer-songwriter Nick Drake, who committed suicide in 1974 at age 26. Martyn still finds it difficult to talk about Drake. ('He just had to split,' is about all Martyn will say.) Martyn's composition. Solid Air was written for Drake a year before he died. Eric Clapton covered Martyn's May You Never and Phil Collins has drummed and sung on several Martyn albums.

Martyn makes a couple of rare appearances this weekend in Chicago. He will do an in-store appearance, which could mean anything from signing autographs to singing a few songs, Friday night at the Inside Track. On Sunday, Martyn appears solo at the Beat Kitchen. He was in the crowd during the club's recent tribute to singer-songwriter Mike Jordan, where he was excited to hear flatpicking for the first time in years. Martyn is in the process of moving here.

That's how he wound up recording last week with ex-Band drummer Levon Helm, another longtime fan, in Studio Five of the Chicago Recording Co. on the Near North Side. It was one of those moments: Helm and Martyn covered the Utah Phillips balled Rock, Salt and Nails, the only non-Martyn composition for an upcoming album. Martyn stood and sang soulful scats with his eyes closed. Helm sat on a stool across from Martyn, and rocked back and forth, tapping his foot and delivering a Delta drawl between long drags from a cigarette.

Originally a temperate ballad, 'Rock, Salt and Nails' was spiced up with a snarly Memphis groove that featured Helm on drums. Producer Jim Tullio smiled: he knew he had a moment. The most remarkable thing about Rock, Salt and Nails is how Martyn's and Helm's totally distinct voices tie the song together. Martyn's gliding slur takes on the ethereal tone of another instrument.

'I've never sung a word in my life,' Martyn said in a midnight conversation with Helm after the session. 'I've always looked at lyric as a gate to the vocals. It wasn't until the last five years that someone even told me I should enunciate better.' Peering out from under his trademark baseball cap, Helm laughed and said, 'You never saw a lyric you couldn't stretch, right?' Martyn responded, 'That's exactly it. It's all music. Harmony and music is more interesting to me than lyric. If I wanted to get lyrical, I would go off and read Yeats.'

When Martyn came to Chicago, he brought five tracks recorded earlier this summer in England. Although a couple of the tunes feature guest appearances from Collins and David Gilmour, Martyn was disenchanted with the results. He turned to Tullio. 'It's sounding better to me,' Martyn said. 'I like the competence, the efficiency and the high level of musicianship I find in America in general but in Chicago especially. This stuff has kind of impressed the record company (Permanent Records). They said, 'Carry on; you might not be as crazy as we think you are.' Then I decided to move here because New York and Los Angeles are too crowded for me. Where I live there is nothing but sheep.'

Martyn met Helm in 1969 through bass player Harvey Brooks. Martyn and his former wife had traveled to Woodstock, N.Y., because they were influenced by the Band's breakthrough Music From The Big Pink album. Last week Helm flew out from his home in Woodstock to spend two days recording with Martyn at the Chicago Recording Co. Besides Rock, Salt and Nails, Helm appears on a Martyn vocal trade-off tune called Just Now.

Helm said, 'I grew up in Arkansas right on the river, so the way John voices music really hits home with me. It reminds me of all my heroes, It sounds like John Martyn, but at the same time I hear everybody from Muddy Waters to, Otis Redding. I can even hear Bill Monroe in there.' Martyn, who listened to Chess Records imports as a 14-year-old, returned the compliment. 'I loved Levon's drumming, singing and his playing,' he said. 'Also, he was the first one to ever show me a watermelon. I had never seen a watermelon, before. Me and my young wife were very innocent. Levon was the first piece of American truth I had seen walk through the door. He was friendly sweet and decent.'