In a Richard Foreman play, the last thing you ask is 'What is it about?'

Watching a play by Richard Foreman is like visiting someone else's dream. Words take on new meanings. Objects and settings have lives of their own. Characters grope through snarled thickets of emotion. The real and the rational tango with their opposites.

In the best Foreman works the effect is alternately puzzling, provocative, unsettling, and hilarious. Few directors can cram a stage with so much visual magic, and few playwrights care to scramble so many metaphors and allusions into such a viscous stew of words.

Sometimes it's just confusing. At other times it's exhilarating. Foreman thinks of it as an artistic circus. For years he ringmastered it from a Manhattan loft called the Ontological-Hysteric Theater, a name he still uses for his troupe. Nowadays he works largely at the Public Theater not far away, also traveling frequently to Europe.

Foreman's latest project is a theater piece called ''Egyptology,'' which opened recently at the Other Stage in the Public complex. It's described as a set of variations on three themes: American adventurism abroad, the seeming exoticism of ancient cultures, and the true exoticism of American ''archetypes and aspirations.''

Whatever one's opinion of Foreman's style, there is no doubt about his determination to follow wherever it leads, allowing few distractions along the way. In recent years he has directed a hit Broadway musical, staged Moliere for the New York Shakespeare Festival, and mounted productions for the Paris and New York City Operas. Unswayed by such ''establishment'' credentials, however, he always scurries back to the utterly original work that satisfies him most - theater pieces that echo the jangling reverberations set off in his own mind by the daunting realities of 20th-century living.

Discussing his new play during a lunchtime rehearsal break the other day, Foreman noted that his shows usually deal with ''a spiritual pilgrimage.'' This time the journey will veer toward the East for a change, but the action will still center on a quest punctuated by musical, visual, and dramatic events.

Not that he wrote the show with this pattern in mind. It just turned out that way. Though his work habits are orderly - almost rigidly so, he admits - a lot of intuition is involved. He jots down ideas and scenes continually, and when the time comes to assemble a new work, he chooses the pages that interest him most, shaping them into a script that changes as the finished play evolves.

It's an unconventional method, but Foreman doesn't think it separates him from dramatists of the past. ''Ideas come all the time,'' he says. ''The same thing happened to Ibsen and other realistic writers. I'm just using a different net for catching what I want to use.''

This ''net,'' he feels, relates less to traditional drama than to modern poetry, music, and painting. That is, the ideas he chooses don't lend themselves to the ''straight line'' of standard storytelling. Rather, they are ''fragments'' of a ''totality'' he tries to assemble onstage, before our very eyes.

The content of a Foreman work grows from his response to our ''eclectic, decadent society.'' He wants to ''mirror the dissociation'' that's a dominant feature of contemporary life, which brings great confusions along with its many opportunities. Hence the anxiety that often permeates his productions - as in his recent ''Penguin Touquet,'' his film ''Strong Medicine,'' or even his outdoor ''Don Juan'' in Central Park last summer. Despite such gloomy currents, however, he always has an antic side.

Foreman has little interest in telling stories onstage, because he feels a story is hard to believe in the artificial context of a theater. ''I can believe a story in a film,'' he says, ''but onstage the plot is wiped out by the sheer physical presence of the actors and the paraphernalia.''

Again, it's not a conventional view, but he has developed his own substitutes for story, in the elaborate visual and sonic environments that interact with his characters.

His philosophy is perhaps summed up in his own rhetorical question: Can the negative things in our surroundings and ourselves be transformed until they radiate energy and lucidity? He says yes. And while his detractors feel ''lucidity'' is the last quality to credit him with, his admirers - not a large band, but an adventurous one - agree completely.