It is one of history’s most enduring questions, up there with the lost continent of Atlantis and the JFK assassination.

Was Mozart poisoned?

Specifically, was he poisoned by rival composer Antonio Salieri?

Old whispers resurfaced in the 1980s, with the success of Peter Shaffer’s “Amadeus” as a play and a movie about deadly envy. But Shaffer did not come up with the idea.

A century and a half earlier, only five years after Salieri died, the Russian poet Pushkin wrote a dramatic poem titled “Mozart and Salieri.” The poem was made into an opera by Nikolai Rimsky-Korsakov. Rarely performed now, it premiered in Moscow in 1898.

Only 45 minutes long, the opera is a tight, intense psychological drama. It will be semi-staged in Kleinhans Music Hall on Friday and Saturday, along with Mozart’s haunting C Minor Piano Concerto, as the Buffalo Philharmonic Orchestra and Music Director JoAnn Falletta present an early celebration of Mozart’s birthday.

“Mozart and Salieri,” which will be sung in English, is remarkable in several ways.

It is respected as the first piece of its length to be written in a neoclassical style. Rimsky-Korsakov quotes here and there from music by Mozart and, briefly, by Salieri. Falletta, who conducted the opera a few years ago with the Virginia Symphony, points out that for the Russian Romantic composer, it was a bold venture.

“Rimsky-Korsakov was one of the greatest orchestrators of all time,” she reflected. “We rely on his music to be brilliant with color, instruments, percussion, woodwinds, extra woodwinds and brass blaring, and there’s none of that here; it’s really pared down. He tries to make it classical. It’s not written in the style of Mozart, exactly. But you have to go to the heart of the music rather than rely on the orchestration, which sometimes we do with Rimsky. This piece is much more to the essence.”

Adding another dimension, Falletta mused that Rimsky-Korsakov, idolizing Pushkin, may have sympathized with Salieri’s feelings of awe and inadequacy. Pushkin died in a duel at 37, just two years older than Mozart was when he died.

With both men’s deaths, the world lost enormous possibilities.

“I really believe if Mozart had lived another 10 years, he, and not Beethoven, would have pushed music into the Romantic age,” Falletta said.

She cited Mozart’s C Minor Piano Concerto, performed this weekend with Enrica Ciccarelli as soloist.

“That concerto was already betraying that kind of individual emotion,” she said. “Mozart is all of a sudden making us feel uncomfortable sometimes. I hope people will hear that in the darkness of this concerto. He’s already thinking in a new world.”

A ‘cutthroat’ society

Salieri gets that same message in “Mozart and Salieri.”

The character of Mozart is more dignified, more complex, than in “Amadeus.” Still his lightness and easygoing humor dismay Salieri, who cannot understand why God has given Mozart these gifts. “My music had all the romance of algebra,” Salieri laments.

His anguished monologues could call to mind Romantic opera heroes. Darren Stokes, who portrays Salieri this weekend, said it reminds him of another role he loves singing, Wagner’s tortured Flying Dutchman.

“It’s much like the Dutchman, the ups and downs of emotion. It’s like in reality where someone talks to himself for 11 minutes. All the emotions, being angry, all the things Salieri goes through.” He laughed. “These are my favorite types of roles.”

Stokes draws inspiration from everywhere – from F. Murray Abraham in “Amadeus” to TV’s “The Big Bang Theory” – as an illustration of how a person can be brilliant in one area and pedestrian in another.

“Quite frankly, in reality, there are individuals, I hate to say this, but there are those who are studious and those who have God-given talent. I had to learn how to sing. There are others who just have a natural gift for it. There’s nothing to do about it,” he reasoned. “Just appreciate it.”

Salieri, he pointed out, is incapable of doing that and just wants to destroy Mozart. As he struggled to understand that, Stokes turned to Jack Nicholson in “The Shining” and also a more unlikely source, a scene from the movie “Mommie Dearest” in which Joan Crawford is beating her daughter.

“Her faculties are gone,” he said. “There’s no weeping, no sorrow, no emotion. If someone can be completely devoid of emotion – that’s what I think Salieri feels at the end.”

The image raises a question one hesitates to ask. Is there a chance Salieri did poison Mozart?

“I think it’s possible,” Falletta said. “We know that Vienna was one of the most nefarious political minefields in the history of art. It was cutthroat, truly cutthroat. The artists and composers would have done anything to survive. Mozart was totally unequipped to deal with this situation. When he moved to Vienna, he was very innocent in everything he did. That kind of thing could have happened.”

‘You shall sleep forever’

Salieri was known as a generous man. He wrote little music after Mozart died and instead taught, giving free lessons to promising students, including Beethoven, Schubert and Liszt.

Yet the rumors lingered. A story comes from a reliable source, the distinguished Czech pianist and composer Ignaz Moscheles. He wrote that Salieri, shortly before he died, brought the matter up with him. His breath ragged, Salieri said: “I can assure you as a man of honor that there is no truth in the absurd report; of course you know – Mozart – I am said to have poisoned him, but no – malice, sheer malice – tell the world, dear Moscheles, old Salieri, who is on his deathbed, has told this to you.”

Moscheles had clearly sensed some trouble, though, because he added: “Morally speaking, he had no doubt by his intrigues poisoned many an hour of Mozart’s existence.”

Jonathan Boyd, who played Mozart in Virginia and is reprising the role this weekend, hit on a similar theory.

“I do not think that Salieri poisoned Mozart using a drug,” he wrote from France, where he was recently singing.

“However, there is a great possibility that he ‘poisoned’ his mind. Among artists there are often mind games that are played in order to prove one’s importance or worth. Sometimes those ‘games’ can become harmful and disturbing.”

“Amadeus” was ambivalent about whether Salieri literally poisoned Mozart. The opera, though, leaves no doubt. Salieri slips the poison into Mozart’s cordial, and Mozart drinks it.

Stokes, our Salieri, is haunted by what happens after that. Having sung Mozart’s “Requiem” – including once at Kleinhans – he feels passionate about the last moments of “Mozart and Salieri.”

“When it comes to the section where he’s made that decision, where he’s going to give Mozart that cordial, and afterward when he sings, ‘You shall sleep forever, Mozart’ ... how do I, in my mind, become a person who supposedly murdered someone? In this opera, he does murder Mozart. I don’t want to make it look like acting.”

Boyd, in faraway France, also confessed to a strange feeling.

He wrote: “As the character of Mozart I am left feeling unfinished. ... Perhaps how he may have felt in real life.”