"We knew that we had a goal set," says Stevie Wonder, wearing the proud smile of a midwife.

"And it has now become a goal met."

That goal was a national holiday commemorating the Jan. 15 birthday of the Rev. Martin Luther King Jr. The 34-year-old superstar was a driving force in getting the legislation passed.

Wonder had a vision of "a national day of love, peace and unity." Fueled by his exuberant "Happy Birthday" song for King, it became a compelling, extremely personal project that occupied him for much of the last two years. Albums and concerts went on the back burner; lost income reached into the millions. Now Wonder is ready to make a little joyful noise again, starting with a King Celebration concert at the Capital Centre tomorrow night.

Legislation for a King holiday had been introduced in Congress as far back as 1968, but Wonder, who inspired and led mass marches and rallies here in January 1981 and 1982 and intensive lobbying on Capitol Hill in 1983, helped make the bill a law. It was Wonder, blind since birth, a star for more than two decades and a folk hero to black Americans, who provided the focus for disparate groups--especially young supporters who might be wary of old-line politicians.

Recounting the process the other day, Wonder spoke softly, and sometimes circuitously, about his passion for the project. Dressed in black leather pants and encased in a woolly black sweater, he punctuates his comments with body slang, as if he's never lost the unbridled adolescent energy that made him a concert star at age 12.

"We got hundreds of boxes of mail from all over the country. But even now I don't think about myself as a leader of this," he says. He adds that he'll "continue my assistance in song and in spirit," working on what he once called Martin Luther King's "unfinished symphony" of social and racial harmony. Like the Vietnam Veterans Memorial, the King holiday seems to have become a tangible symbol of a healing process.

Asked if the legislation capped his political career, Wonder slips into a gravelly Don Corleone voice and says, "It's the end! If I don't put a record out, I'll be broke."

Later, the thought of holding office suddenly seems more intriguing. Wonder cuts to an imaginary press conference: "As your president, I'd like to say to you that as long as you buy the albums that I did 20, 30 years ago, we'll be in good shape!"

Seriously, though, Wonder doesn't see himself as a politician. "I like being able to say what I feel," he joshes, adding that he's "long behind" on his album. "Motown would love to see me get back to work. They call me every day and tell me how many copies Michael Jackson sold. And I say that's great because I bought about six copies myself."

Wonder has not released an album since mid-1982. Even that effort, "Musicaquarium," was a two-record "best-of," buttressed by only four new songs. His last full studio album, "Hotter Than July," came out in October 1980.

"It's not easy going years without putting a record out," admits the man with a reputation as a compulsive creator. "Especially when you hear other people's records on the radio. But you have to decide: do you want to do something just to hear yourself on the radio or do you want to do something that you feel really comfortable hearing on the radio, no matter how long it takes? That's the kind of gamble that I've had to take in my life."

Being faced with a loss of income also called for a decision. "It's not that music is not as important to me as this, but it afforded me the opportunity to inspire something like this to happen. I took the chance and I'm very happy because what has happened is far greater than what any money could ever have given me."

Wonder says he first became aware of King in the mid-'50s, when he was a small boy in Detroit. "I heard about this man. I didn't know his name but I knew he was 'helping the colored people out down South.' I didn't know anything about what that was all about, not understanding at that time in my life the difference between white and black and that whole vibe. But I knew that there were people being treated wrong and that he wanted to correct that situation. That stuck in my mind."

The only encounter Wonder had with the civil rights leader came in 1965 during the national airline strike. "We took this Cessna plane from New York to Chicago and the pilot let me fly the plane," Wonder recalls with a chuckle. "I pushed the wrong thing and we started going dooowwnn . . . Oh my God! When we got to Chicago--he was having a rally at Comiskey Park--he said, 'Young man, I'm very happy to meet you--you're doing a lot of things for young people.' " One gets the feeling that one sentence means more to Wonder than the 14 Grammys he's acquired in the last decade.

Wonder has spent much time since his breakthrough "Music of My Mind" album exploring synthesizer and other technologies, many of which are now usable by the blind, "which makes it easier for me to get into that dimension of computers as sound. I've taken a lot of time out studying, learning that stuff. I wouldn't want to put an album out with just the sounds that are available."

And that led to long waits between albums even before the King holiday crusade. Admiring Motown's patience even as he's testing it, Wonder admits, "I have songs, I do, I do." Pressed a little for details, he inquires, "Are you working for Motown? Well, the album title is 'People Moves, Human Plays' and hopefully it's going to be out in 1984." Wonder leans toward Los Angeles and says in a mock cowboy tone, "You gonna get so much product, buddy, you gonna wish he'd never put a record out." It's a threat Motown would love to live with.

Wonder and Motown are kicking around his desire for another double album ("They don't want me to do it"). Someday, he adds, there will be a live album ("I wish we had recorded the last tour; we had some really beautiful moments"). Several new songs will be unveiled at the Capital Centre, including "It's Growing," "Go Home" and "Overjoyed."

"There are a few things I want to do this year," Wonder says. "I want to get Wonderlove's album out . . . I want to do all the things I said I was going to do for the last thousand years. People have patience, but this is ridiculous."

And, like everyone else in the music business, he wants to get into video. His only effort so far is the " 'Ebony and Agony' . . . sorry, 'Ivory' " job with Paul McCartney. "I have ideas for the songs, and the market is going in that direction. I think 'Thriller' is a great video, and Thomas Dolby's 'Dolby Blinded by Science.' " Wonder doesn't explain just how he saw these videos, but adds, "I want to do video in another kind of way so I'm still thinking that. We're thinking of calling it Blind Eye Productions."

Although he's been relatively inactive musically, Wonder has continued his collaborative works. He plays and sings backup on the Gap Band's "Someday We'll All Be Free," Donny Hathaway's song honoring King. He recently recorded with Elton John and Donna Summer. "And," he adds, "I hope to, . . . for the first time in my life, take an honest vacation, go far away and be with myself."

As for what he's given up in the last two years--money, momentum--Wonder says there are "no regrets. None at all. I just feel bad that I haven't fulfilled some of the promises I've made. I apologize to everybody, whomever, for that, because I try to make my word straight out. But I'd like to think that what I'm doing is far bigger than a record, and far bigger than me. I have no problem with that."

Now "we can start bringing the energy to positive," Wonder says. "I think of John Lennon. Every time I hear 'Imagine' I cry because I think of how beautiful his imagination was, how incredible, and how anytime that there is that positive like that, there is a negative. But if there are more of us who are positive, we protect that positive spirit from the potential negative."

And if the King holiday legislation had not passed?

Wonder insists he "would have continued on. But I would also have continued recording. A great deal of time and energy have been spent working on making this happen, but I didn't think it was going to take any more time. I knew it was going to happen. Like when I did 'Songs in the Key of Life,' there was a certain point in all of that when I knew it was all going to be fine, that the album would be one of my better ones. I messed around with it, went back and forth with it being a single or double album . . . it didn't sound like anything that I'd heard, so I was afraid, in a sense. But I believed that it was right.

"I didn't hear people saying, 'It's going to happen, we're going to have a national holiday,' but I believed it was going to happen. It's right, it's time. I believed!"