Despite its deserved reputation as a cultural landmark of the first order, the Robert Wilson-Philip Glass multimedia production "Einstein on the Beach" has been seen by only a small number of people, judged by the usual standards of mass consumption. Tonight this will change, courtesy of public television, which will broadcast "Einstein on the Beach: The Changing Image of Opera" as part of its "Great Performances" series. The 60-minute program, a documentary on the restaging of the work for the Brooklyn Academy of Music's "Next Wave Festival" two years ago, can be seen locally on Channel 26 starting at 9.

"Einstein" had its world premiere in Avignon, France, in 1976. It was next given in two sold-out performances at the Metropolitan Opera the same year, but then waited eight years for a revival at BAM. That's been the sum of its exposure to date, apart from the brisk-selling album of Glass' music. Thus the PBS gambit represents a big step forward in bringing the work to a potentially broader audience.

One couldn't help wonder, however, whether a production that depended so heavily in its stage performances on mammoth spatial scale and live ambiance would translate at all successfully to the small screen. The miracle is not only the extent to which it does succeed, but the revelations that ensue from the close-ups and intimacy only TV can provide. Moreover, the impact of the performance and rehearsal excerpts -- the original work ran 4 1/2 hours -- is buttressed by some wonderful footage of Wilson and Glass talking about their artistic lives and methods.

I had the good fortune to catch both the Met and BAM performances, and to my eyes and ears the television program reconfirms the haunting power of the work despite the drastically reduced dimensions. How it will strike a first-time viewer is hard to estimate, but anyone open to adventurous experience should at least be able to sense the enormously original flavor and scope of the production.

The program's title may be a bit misleading, however. "Einstein" has about as much to do with mainstream or even most contemporary opera as Mick Jagger has to do with lieder singing. The legendary scientist is quoted by the narrator of the program: "The most beautiful experience we can have is the mysterious." The heart of the Wilson-Glass opus, with its mesmerizing choreography by Lucinda Childs, is mystery, from start to finish -- the sense of mystery one feels when contemplating the infinite cosmos or the riddles of human consciousness.

Yet the imagery of "Einstein" ranges from stylized spaceships to things as mundane as a chorus of singers furiously brushing their teeth, or Lucinda Childs muttering over and over the words of a commercial for soft contact lenses. As Glass puts it in the interview portion of the show, "If you're expecting 'Oklahoma!' you're going to be pretty disappointed."

"What we did with Einstein," Glass explains, "was to take a person and make him the subject of the piece. In a way, the person replaces the plot, or story." Or in Wilson's words, "It doesn't tell a story . . . it's not trying to illustrate Einstein the way history books do. It's trying to present a poetical interpretation of this man."

There's a wonderful vignette further on when Wilson illustrates the importance of precise timing in his concept of stage action by imitating Jack Benny telling a joke, spurring the laughs by timing the body English that signals the punch line. Wilson also helps the viewer toward understanding with an explanation of his use of three traditional modes of pictorial art -- portraits, still lifes and landscapes -- in the visual structuring of "Einstein."

For those whose appetites may be whetted by the program but feel frustrated by the lack of opportunity to see more of the work, there may be some consolation. A longer, tailored-for-video version of "Einstein" is at the talking stage at PBS, in consultation with Wilson and Glass.