There’s not too much I can add to the many tributes and essays about Stephen Sondheim, who died yesterday at the age of 91, but I feel I owe him a special salute for his ethics. Ethics is not a common trait in theater, or in show business generally. Sondheim, one could argue (and I will) built his career on ethical values.

The Times has three excellent pieces: a front page obituary, a report on a final interview, and an appreciation by critic Jesse Green. I don’t disagree with any of them, nor do I dispute Sondheim’s importance to musical theater and the culture, which justifies his superstar send-off. None of them come right out and say what I believe to be obvious, if inconvenient: for all his influence, Sondheim represented a fascinating, elitist, dead-end for musical theater, which he was determined to elevate whether it was healthy for the genre or not.

Musical theater arose from humble, populist origins like the British music hall, and it was generally accepted to be a way for ordinary people to have a good time without having to think too much. That model served the genre, and the industry, well until Sondheim’s mentor, Oscar Hammerstein II took off from where only scattered experiments like “Lady in the Dark” and “Pal Joey” had previously ventured to bring serious topics and dilemmas into song while still sending the crowd home humming. Sondheim, once he had freed himself from writing words to established composers’ tunes in “West Side Story” and “Gypsy,” deliberately sought darker, more complex stories to musicalize than even Oscar would dare attempt.

The inconvenient truth is that the musical-going public never really went for it. None of Sondheim’s musicals in which he wrote lyrics and music were as successful as “Gypsy” except for “A Funny Thing Happened on the Way to the Forum,” and that was a show that celebrated low-brow humor (though from a high-brow source). The rest were loved by critics and other show biz types, won awards, but they usually lost money for investors, and added few songs to the Broadway canon that anyone would voluntarily play in the background at a party, or that anyone without training could spontaneously sing.

Sondheim has one probably undying classic on his resume, “Sweeney Todd,” which is entertaining in the way horror movies are entertaining with humorous Gilbert and Sullivan overtones. The rest are dated, flawed, too difficult to produce or pretentious, though all are fascinating to watch and think about.

Sondheim didn’t care. He had a vision for the musical and for his art, and he was determined not to be deflected from it for such pedestrian goals as fame, popularity or money. “I certainly feel out of the mainstream because what’s happened in musicals is corporate and cookie-cutter stuff,” he told one interviewer. “And if I’m out of fashion, I’m out of fashion. Being a maverick isn’t just about being different. It’s about having your vision of the way a show might be.” Thus he insisted on never repeating himself. “I have always conscientiously tried not to do the same thing twice,” Sondheim said.

Yet in the business of the American musical, the formula was and still is that once a show was a hit, the task is to find a way to repeat what the audience liked so much. Thus the anti-Sondheim, Jerry Herman, followed his boffo “Hello Dolly!” with another musical about an indomitable middle-aged heroine, “Mame,” both with a brassy, show-stopping title number (that Louis Armstrong could turn into a best-selling single.) This kind of cynical Gerry Puckett and the Union Gap approach was beneath Sondheim.

I consider myself one who appreciates rather than loves his work, but I know it well, and I can’t say Sondheim ever appeared to be ripping off himself like, for example, Rodgers and Hammerstein often did , or Lerner and Lowe did with “Camelot” mirroring many of the numbers in their biggest hit, “My Fair Lady.”

Sondheim valued artistic integrity above all. He was an original and versatile composer though not a gifted one, but perhaps the most technically brilliant musical theater lyricist of all time. That is not to say, in my terms, he was the best. You could always (at least I could) sense Sondheim sweating to be clever,multi-layered, deft, and perfect, something the more intuitive lyricists like Noel Coward, Larry Hart or Allen Jay Lerner never seemed to let us feel.

He refused to cheat. In “Mame’s” “We Need a Little Christmas,” Jerry Herman rhymes “laughter” with “ringing through the rafter.” That kind of thing drove Sondheim nuts. Paul McCartney, as gifted a melodist as Sondheim was a lyricist, tells the story of singing “Hey Jude” for the first time for John Lennon, and getting to the line that says, “Don’t carry the world upon your shoulder” to rhyme with “colder.” He stopped and said, “Don’t worry, I’ll fix that…it makes me think of a pirate with a parrot on his shoulder.” Lennon replied, “It’s fine, leave it alone; I like it. The meaning is clear, and nobody will care.” Sondheim cared, and that was enough to keep him striving for perfection.

I said at the start that I felt I owed Sondheim a special salute. 20 years ago, I wanted my little professional theater company, the American Century Theater, to revive “The Frogs,” an experimental Sondheim musical, based on the Aristophanes comedy, that had its first production in a Yale swimming pool. For obvious reasons, the show had seldom been performed since, and never in the Washington, D.C. area. I had what I thought was a fun and dynamic way of doing a dry version, but when I applied for the rights, I was told that they were unavailable. So I wrote to Sondheim directly, explaining our company’s mission and why I wanted to do the show.

To my amazement, he wrote back, in a long, hand-written letter. There was no hint of the “famous theater artist deigning to speak with small-time schmuck” feel to the letter; I’ve gotten plenty of those. It was genuinely apologetic, and it seemed like it was important to Sondheim that I understand that he wasn’t being casually obstructive. Sondheim famously was liberal in allowing directors of his shows to try new approaches. (The soon-to-open revival of “Company” casts Bobby as a woman, with Sondheim’s approval.) Sometimes his accommodating spirit backfired on him, as when he let Tim Burton miscast non-singers Johnny Depp and Helen Bonham Carter in the film version of “Sweeney Todd.” But this was the Golden Rule in action for Sondheim: artists all crave the freedom to take risks and massage the works of others in the hopes of discovery, and he wanted to give them a chance.

He wanted to give me a chance to try my crazy idea for “The Frogs,” too, he wrote, but a Broadway revival starring Nathan Lane was in the works with new material. “I don’t know if the new version will work, and, frankly, if your production turned out better than ours, it would not be good us. Please accept my apology. I wish I didn’t have to frustrate and disappoint you.”

That was kind and considerate; he didn’t have to say that. So in addition to everything else he accomplished, Stephen Sondheim managed to stay a nice guy after he was rich, famous and idolized.

That’s a least as difficult a trick as “Finishing the Hat.”

Here is what I believe to be the greatest song Stephen Sondheim ever wrote, from the only musical of his I directed, “Follies.” It is simple, powerful, you can understand every word, and it epitomizes Sondheim’s vision of a song as a mini-play, as the emotionally fragile Sally continues to be tortured by the betrayal of a lost lover, long ago.

The damn thing kills me every time.