TO THE AVERAGE theater-goer, the producer is the invisible man of any production. You're always aware of the actors' contribution, and you can make an educated guess at what the director has done, but what on earth is the producer supposed to do?

Hal Prince has answered this question--in detail--but in so doing he has raised another one: why on earth would anyone want to be a producer? The producer has to do all the dirty work. He has to bargain with powerful unions and soothe touchy artistic temperaments. He has to put his foot down and say no a lot, and everybody ends up hating him. He gets most of the blame and little of the credit--at least from the general public--and worst of all, he always has to worry about money.

As it turns out, Prince, who over the past 26 years has risen to become one of the top producers in the country, doesn't really know why anyone would want to be a producer, either. In fact, he doesn't really want to be a producer, he wants to be a director. But because he has a pathological fear of being fired, he can't bring himself to work for anyone but himself.

The fact that such an eminent producer hates producing is not the only contradiction in this aptly-titled book. It's refreshing that Prince is honest enough to disagree with himself in public, but it can also be frustrating. For instance, he follows his comment that the star system is beginning to break down in some movies "to the artistic advantage of those movies" with a footnote that confesses, "I really don't believe this about movies. I would give my right arm for Tracy, Colbert, Gable and Lamarr in Boom Town."

Although the reader is left wondering what Prince really does believe, it's easy to sympathize with his ambivalence. There's something seductive about big, flashy star-studded musicals with lots of dancing and songs that you sing to yourself on the way out of the theater--Damn Yankees, West Side Story, A Funny Thing Happened On The Way to the Forum, Fiddler on the Roof, the shows that made Prince famous in the fifties and sixties. But at the same time, there's a nagging feeling that all this display is not really "art," that it's all contrived and calculated for the sole purpose of making money.

This feeling seems to have nagged Prince, too. Over the years he has been resolving the inner contradiction between the businessman and the artist in favor of the latter, moving fairly steadily away from the more traditional sure money-makers to riskier experimental ventures. He has metamorphosed from a straight producer to a producer-director, delegating more and more of the dirty work and concentrating on the creative aspects of putting a play together.

The first part of the book, which is devoted to Prince's earlier experiences on Broadway, tends to be boring. Prince dissects one production after another, and they all begin to sound alike--find the love interest, the comic relief, figure out what will sell. There are few anecdotes, and, although there are quite a lot of names, few characters. If Prince had concentrated more on only one or two productions, carefully analyzing the dynamics of the collective creative process that lay behind a particular play, he might have provided some more insight into the way a hit musical is mounted. As it is, he has included just enough detail to be tedious, but not enough to be interesting.

AROUND ABOUT 1966, when Prince produced and directed Cabaret, things begin to liven up. What drew him to the play, he explains, was "the parallel between the spiritual bankruptcy of Germany in the 1920s and our country in the 1960s." At the first rehearsal, Prince showed the actors a photograph of "a group of Aryan blonds in their late teens, stripped to the waist, wearing religious medals, snarling at the camera like a pack of hounds." The cast placed the picture in pre-war Germany. Actually, Prince pointed out ominously, it was a gang of toughs fighting the integration of a Chicago school.

Perhaps it was not a startlingly original comparison, but it was a break from the conventional approach to a musical, and Cabaret was an artistic as well as a commercial success--perhaps the last hit Prince will ever produce. He felt that he had compromised too much on Cabaret, imposing a plot on the original Christopher Isherwood stories, adding a subordinate story for the sake of love interest, toning down some of the biting satire. "My shows don't do as well now at the box office as Cabaret did because now I do them exactly as I want to do them," Prince writes.

A case in point is Prince's 1972 production of Follies, which was almost unanimously praised by the critics but which lost $665,000. Although he is happy he did Follies, Prince says he could not do it again because he "could not in all conscience raise the money for it," not because it was a financial flop but because its subject was really the death of the Broadway musical. He quotes a review that appeared in The Crimson as summing it up best: "...there is no getting around the fact that a large part of the chilling fascination of Follies is that its creators are in essence presenting their own funeral."

Prince seems to be saying, rather obliquely, that the Broadway musical is in fact a dying breed. But--another contradiction--he continues to work on Broadway. The book is actually a condemnation of the whole Broadway system, which constantly places artists under the constraints of making money. The theater business should not be a business, and Prince seems to recognize this. He complains that when Candide, perhaps his most unconventional musical to date, was transported from a fourth floor theater in Brooklyn to the Broadway Theater, much of the original spark was lost.

Money became a factor--the actors had to sign contracts, the musicians' union forced Prince to hire 25 musicians when he only needed 18, so seven of them get paid for sitting in the basement. The grandiose lobby of the theater didn't fit the mood of the play, so Prince sprinkled sawdust on the marble floor and set up hot-dog-and-beer stands. And the Broadway audience gave the play a hostile reception, complaining about having to sit on bleachers and having their view obstructed by scenery--both deliberate and artistic innovations. Prince complains bitterly that all the Broadway audience cares about is "creature comforts"--"If you gave those people beds, they could come in and sleep and we wouldn't have to worry about what we put up on the stage."

PRINCE BLAMES himself and other Broadway producers to a certain extent for this state of affairs--for "desensitizing" the audience--but he insists that part of the responsibility is theirs. What he doesn't seem to realize is that the Broadway system, by forcing up ticket prices and making financial success the sole criterion, has created its own monster, the Broadway audience. And now that entrepreneurs are offering unfamiliar fare, that audience is dwindling. They are unwilling to pay $15 a person to sit on bleachers and risk being offended.

The musical is changing, and the production of the musical will have to change with it. With wages and prices rising, it's more difficult to stage lavish shows, even leaving aside the question of whether such shows are artistically desirable. To make the theater accessible to everyone, financing should come more from the government and from foundations, and less from private investors and the box office. And much of the dirty work that Prince complains about could thus be eliminated. The contradiction between artist and businessman would be resolved simply by acknowledging that it is impossible to create a show in the same way you would finance a profit-making venture Although this seems the most obvious point that emerges from this somewhat confusingly written book, it is something that Prince never seems to grasp. He just accepts the contradiction. Maybe he figures that's just show business.