Gil Scott-Heron, who celebrates his 33rd birthday with a pair of concerts at the Wax Museum tonight, has the touch of a prophet and griot about him. His 10-year career has been marked with songs and rapped poems addressing important social and political issues, most frequently from the black perspective, but also from the colorblind concerns of the humanist-activist.

His timing has not always been good, but it's usually a case of the song preceeding the issue--"Shut 'Em Down" appeared before Three Mile Island, "H2O Gate Blues" before Nixon was exposed; "From South Africa to South Carolina" succinctly connected Third World and black American struggles for freedom.

When Scott-Heron's new album, "Reflections," came out in October, it included the lengthy rap "B Movie." At the same time that President Reagan decided to start reminiscing about the good old values of Hollywood, Scott-Heron was utilizing much of the same imagery for a scathing attack on Reaganomics. "It's one of the few times we had released an idea that was drawing public attention at the same time," Scott-Heron says in a warm, deep voice that rumbles for attention. "If 'B Movie' had come out when I wrote it a year ago, I don't suspect it would have had the impact that it had last fall--after people had lived with Reagan for a while."

The 12-minute cut received extended airplay on the country's black stations; New York superdeejay Frankie Crocker would even play it four times in a row. In an astute move, Arista Records sent a copy to every member of Congress; many wrote back with positive comments on its satire. But the seriousness and sense of prophecy weren't lost on them either, and that's one of the constants in Scott-Heron's work.

"If you wait until after Three Mile Island to do songs about nuclear power, you are dealing with the headlines, not with the substance of it and how much of a problem it is," he says. "If you wait until something of that nature goes down, if you don't speak about it in advance in terms of the possibilities, you're co-opting on someone's misfortune."

Scott-Heron's seven albums are crowded with songs that reflect an acute political consciousness not often evident in American pop music. "Gun" dealt with a scared ghetto father's feelings about gun control. "We Almost Lost Detroit" addressed a near-nuclear accident in 1966. "Tuskegee No. 626" recalled shameful and secret government syphilis experiments on unsuspecting black subjects. "Not Needed" captured the emptiness of forced retirement, while "Pieces of a Man" dealt with a man losing his job and "snapping out." "Home Is Where the Hatred Is" and "The Bottle" were bitter attacks on drug abuse and alcoholism; "Waiting for the Axe to Fall" is an old song about ghetto life that seems more relevant than ever.

The lanky songwriter was also one of the few black acts to be involved with Musicians United for Safe Energy, again reflecting the communality of his concerns. "The problems that I often define are from the black perspective and experience," he explains, "but when I'm describing a situation that all people encounter, should it be disregarded because I'm black? There are a whole lot of white people in the world who are oppressed. It doesn't seem to be to anybody's advantage to just concentrate on areas that affect a narrow part of our community or the community at large.

"Some black folks seriously asked me what I was doing going off into this nuclear power thing, as though it was something that only affected white people," he adds incredulously. "But nuclear power is an equal opportunity destroyer. There's absolutely no racism involved with the threat of nuclear power. I feel that this is something that's happening on Planet Earth and it's not going to behoove me to ignore something that could have a serious effect on my life just because there aren't many black people involved in it yet."

Scott-Heron's activist concerns have extended black protest music from its traditional centers, blues and gospel. Elements of the Last Poets and Richard Pryor surface in the swaying urban funk and reggae densities of his music, though Scott-Heron is quick to point out that socially pointed and politically focused songs "by no mean dominate where I'm coming from or what I'm all about." That material has admittedly gotten the focus, but he sees himself as "a developing artist who's more well-rounded than most people have given me credit for."

Ten years ago, Gil Scott-Heron fit the profile of the classic "revolutionary intellectual." He'd published two books before he was 21, including the prophetically titled "The Revolution Will Not Be Televised." While getting his master's at Johns Hopkins, he spent four years teaching at Federal City College. Meanwhile, the "revolution" seemed co-opted by a false sense of security, progress and fashion.

Somehow, though, Scott-Heron has maintained that sense of purpose and change, merely tempering it with sophistication. The little urban gorilla-guerrilla figure that adorned his album sleeves has been retired. Each new album has sounded more sophisticated as the medium is streamlined to deliver the message to more people. Still, that spark of change undulates beneath the smooth pop surface. "Americans are pretty instant minded," Scott-Heron says caustically. "You can get damn near everything you want in America instantly. And when they heard about revolution and didn't get it instantly, they said, 'There must not going to be one.'

"But people who have examined revolution primarily as a process of social change have been more concerned with bedrock organization. You have to look at Zimbabwe--they fought for 100 years and it might take them X number of more years before they have a government and a society that can be beneficial to everyone there. People in America, if you said, 'We need to fight for 100 days,' they'd say 'Get back to me in 90 days. I'll see what I can do with you the last 10.' They don't have that kind of persistence, that kind of determination."

Scott-Heron's already started work on his next record. It will include some more poems, and a song called "No Exit," "about people trying to run away from responsibilities." It's not autobiographical.