THE BASIC impulse of Joe Jackson's career has always been to move forward, to keep those creative wheels turning, to never look back.

Until now.

Last year, Jackson realized he was coming up on the 25th anniversary of the formation of the Joe Jackson Band and the release of its classic debut album, "Look Sharp!" There would be two more Joe Jackson Band albums -- "I'm the Man" and the reggae/ska-fired "Beat Crazy" -- before the band broke up in 1980, at which point Jackson began to seriously distance himself from his post-punk/new wave origins.

From the early jump-blues revivalism of "Jumpin' Jive," the sophisticated pop of "Night and Day" and the urbane jazz-informed "Body and Soul" to soundtracks and symphonies, Jackson seemed intent not only on not repeating himself, but also not defining himself.

"As an artist, you're working on intuition, with the material you have in front of you," Jackson suggests in response to a question about his impressively diverse yet confusingly eclectic catalogue. He insists there's no great difference between the pithy pop songs of the old and new Joe Jackson Bands, or between his neo-operatic song cycle based on the Seven Deadly Sins (1997's "Heaven & Hell") and his jazz-flavored, classically structured symphony for electric guitar and electric violin (1999's "Symphony No. 1," which won a Grammy -- Jackson's first -- for best pop instrumental album).

Certainly, there's no dramatic change in his mental approach.

"It's not as though when I'm doing other things I'm consciously cluttering my mind," Jackson explains. "Whatever I do, I try to make it as clear and simple and concise as I possibly can. It's just that sometimes you have different material and you take it in the direction it wants to go in. To me, it's very much like the difference between writing short stories and writing a novel -- there's really no great difference in that it's a question of structure as opposed to anything else. I don't think of it as switching gears, or now I'm going to put this hat on and be in this genre instead of this one. I don't think that way.

"If I'm doing a pop structure, then I'm doing my utmost to write a great pop song and that's just as demanding, and as difficult, as writing a symphony."

Ironically, "Symphony No. 1" was as much a wheel returning to an old point of reference as the reunited Joe Jackson Band's "Volume 4." After all, Jackson studied keyboards, composition and orchestration at London's Royal Academy of Music in the early '70s. After graduating, he took a brief detour, working as musical director for the Portsmouth Playboy Club, before forming a band with bassist Graham Maby, drummer Dave Houghton and guitarist Gary Sanford.

Their debut album included the classic plaint, "Is She Really Going Out With Him?" Now, after a break of 22 years, is he really going out (on tour) with them?

"I'd been in touch with the other guys, especially with Dave, but we never actually played together," Jackson recalls. "But I'd seen them play and I knew that everyone could still play and that we were all in good shape. No one's terribly fat or messed up on drugs or dead or anything." This is spoken by a man proud of the 26-inch waist he maintained then and now.

Old conversations and friendships were easily rekindled, but the notion of reuniting for an album and tour was a tougher sell, Jackson admits.

"The hard part was convincing everyone that I was serious about doing it -- they didn't believe me. But they were all very enthusiastic. At first I think we were all a little bit nervous, but it only took a couple of rehearsals to realize that this band had a great chemistry then and it just came back really easily. We were actually a little surprised at how easy it was."

As it happened, Jackson already had written six of the songs that appear on "Volume 4." "I was writing without having a clear idea of what the next project was going to be, but I was enjoying writing, I guess, simpler songs again after having done a couple of very ambitious projects in the '90s. I started to think those songs would actually work with that band and I felt kind of inspired by that and started writing for the band."

Before recording, the band went out and played a series of concerts in England. "We could have just rehearsed and gone straight into the studio but that would have been too safe," Jackson says. "I wanted to add the element of danger you get from playing live." A bonus disc on the new album offers new live versions of six Jackson classics recorded on those dates.

Like its long-ago predecessors, "Volume 4" was recorded on 24-track analog. "It just seemed like the right way to do it," Jackson says. "It's how we did it back then and there was really no need, no reason, to do it any other way. I wanted it to sound like this band, to sound real, to sound live; I didn't want to layer lots of guitar tracks or synthesizers or anything like that. And we fell back into a certain way of working the arrangements, so there was never any doubt that it was going to sound reminiscent of the early albums. But the intention was not just to re-create that or have it be just an exercise in cheesy nostalgia."

The only changes Jackson will concede are in his voice and his lyric-writing. Jackson has often described that voice as a character actor rather than a leading man, but he now seems ready for his close-up.

"Singing is the hardest thing that I do by a long way -- the least natural thing and the thing I've had to work most at. I only started singing in the first place because I was writing the songs and when I tried to get other people to sing them, it didn't work. It never sounded right, so I became a singer by necessity. And then I became a better singer by necessity, too, because without some sort of technique, I'd be losing my voice and having to cancel shows all the time. I've desperately gotten a lot better, to the point where I can almost enjoy it.

"What I've always wanted to do is to write music, be a composer and songwriter. That's the most important thing."

Of his early writing, Jackson has mixed emotions.

"I certainly was naive, and I was naively cynical. There's a sort of attitude that I had -- I was 23 when I recorded 'Look Sharp!' I mean, what do you really know at 23? Typically, you think you're much smarter than you actually are and you're going to be more cynical than you have a right to be, and I hear that on various songs.

"I think a lot of that stuff is really quite immature, especially the lyrics, but I also think it's pretty good and I quite enjoy it and it's fun doing some of those songs again, as well as bringing something of the past back into the present."

The current tour will feature Joe Jackson Band songs old and new as well as songs from "Laughter& Lust," "Night and Day II" and "Blaze of Glory," Jackson's song cycle about a boomer rock 'n' roller coming to grips with middle age and maturity. Just don't expect anything from "Jumpin' Jive" or some of the early '80s albums.

"It's hard to do some of the songs from [the first] 'Night and Day' with this lineup, but some of the later albums actually work quite well," Jackson says. He probably wasn't going to be able to please everybody anyway, the price of creative explorations and a refusal to be pigeonholed.

"When I meet someone who doesn't know anything about me and they say, 'So, what kind of music do you do?', I really don't know what to say," Jackson says. "I feel stupid! I wish I could say, 'I'm a country-western singer' -- it would make everyone's life easier, but I just can't because it's not me and it would be phony. Apparently I'm a little more diverse than a lot of other people and I didn't realize that. I thought it was allowed -- that's all I can say. I was naive because I thought it was okay to be diverse, to be creative, to be eclectic."

So the wheels kept turning, and eventually Jackson found himself passing a familiar point of reference. "That's a natural part of the process," he suggests, as is the reissuing of his classic catalogue. A couple of years ago, Universal (which now owns his old label, A&M) rereleased "Look Sharp!" and "I'm the Man", along with two of what Jackson has dubbed "redundant compilations." But that seems to be it -- no "Beat Crazy," "Will Power," "Big World," "Jumpin' Jive," "Blaze of Glory" or "Night and Day."

Jackson says he's been trying to regain control of his catalogue, "but the Evil Empire, aka Universal, just don't want to know. They're simply not interested, so there's nothing I can do. They won't do anything that they're not absolutely contractually obliged to do and have no intention of rereleasing those albums. It's a sore point."

JOE JACKSON BAND -- Appearing Monday at the 9:30 club with Mary Lee's Corvette. * To hear a free Sound Bite from Joe Jackson, call Post-Haste at 202-334-9000 and press 8121. (Prince William residents, call 703-690-4110.)

The reunited Joe Jackson Band will play both classics and tracks from its new album, "Volume 4," on its current tour.