NEW YORK (NYT NEWS SERVICE).- Beethoven had to present his only opera three times before it won success. It was premiered as “Fidelio” in 1805, revised as “Leonore” in 1806 and revised again in 1814 as the “Fidelio” we know today. Everyone now calls the first two versions “Leonore” to distinguish them from the famous one — but they are far from identical, because Beethoven was under intense pressure to shorten and simplify after the mixed reception in 1805.

What he originally wrote, though, was not some kind of student effort; we’re talking about a composer who already had the “Eroica” Symphony behind him. The conductor René Jacobs has recently asserted — backed by a recording — that the 1805 version is the best overall, and he is not alone. It is the version Opera Lafayette will revive in Washington on Feb. 26 and New York on March 2 and 4, conducted by Ryan Brown. But this time, it will be performed with a tenor aria nobody has heard since the year it was written.

Or, rather, with a guess — mine — at what that aria might have sounded like. The original was destroyed when scores were cut up so that some pages could be recycled for the second version. Revision was no light task in pre-photocopy days. Everything had to be done by hand, and they weren’t thinking about posterity; they were thinking about tomorrow’s rehearsal.

The scene in question is the first appearance of Florestan, a political prisoner wasting away in a dungeon when his brave wife, Leonore, takes a job at his prison in hopes of getting him out. His soliloquy consists of a grim prelude, a spacious recitative and a grand aria in the standard two-part (slow-fast) form. That outline applies to all three versions of the opera, but every section is musically different in each.

The first time around, Beethoven had tenor troubles. A reviewer wrote that Carl Demmer, the 1805 Florestan, was “almost always” singing flat. Looking toward the 1806 revival, the composer made a revision of the slow movement — almost certainly a simplification — and he at least considered dropping the fast movement altogether.

But then a replacement tenor was found in Johann August Röckel — the only change in the original cast. Beethoven was happy with him, but he still had to shorten the opera. Two sections got lost on the cutting room floor. One was the original slow movement; the shorter, revised one was kept. The other was the whole first section of the fast movement, a solo in F major with obbligato flute, in which Florestan recalls happier days with Leonore at his side. This was followed by an agitated section in F minor, in which he hopes his wife will realize he did the right thing. In 1806, that second part was left to stand by itself after the rewritten Adagio.

All previous revivals of the 1805 opera have had to content themselves with the 1806 aria, because the music had vanished. How do we know it was ever there? Partly from a few surviving pages: Under time pressure, you weren’t going to throw out a sheet if one side had music still needed for the new score, or if you could update it by overwriting a few lines. But for the music on the missing pages, our only clues come from the multiple drafts preserved in the “Leonore Sketchbook,” 346 pages of scrawls and chicken-scratches now bound together into a forbiddingly vast volume in the State Library of Berlin.

Beethoven’s sketches are impossible to read in any ordinary sense of the word reading, but a whole scholarly industry has grown up around decrypting them. The drafts for the lost aria have been thoroughly examined, some of them provisionally transcribed. The original notebook can now be studied online through high-resolution digitizations. But deciphering the sketches, and deciding which to use, is just step one. Beethoven drafted mostly “top line” melodic ideas, and the elements that make his music sound like itself are hardly concentrated on the top line. To make a performable score, you have to imagine how he might have supplied those elements.

My nomination for that job was not due to any special expertise on Beethoven, but to my long experience with filling gaps. In revivals or editions of obscure operas, it’s often necessary to compose missing bits, ranging from a couple of bars accidentally skipped by a copyist back in the day to whole accompaniments for arias whose orchestral scores got lost. Or even, in a few cases, fresh invention based on nothing but a libretto, for necessary continuity in an opera that’s come down to us incomplete.

An Opera Lafayette board member had heard one of my reconstructions — an unfinished movement from Donizetti’s Symphony in E minor, played last summer by the Teatro Nuovo orchestra — and liked it. Would I dare try Beethoven? I answered that I would study the sketches and give it a shot if they suggested something to my imagination.

They did. In the earlier revivals of “Leonore” I had heard, the Florestan aria always seemed a bit lackluster: noble resignation followed by a brief expression of anxiety. What quickly became clear from the sketches is that the part Beethoven cut out had been the heart of the scene.

“He draws a portrait from his breast,” the libretto says, and a solitary flute pierces the gloom like sunlight through a crack in the prison walls. Florestan speaks of the “beautiful days” gone by; of his beating heart; of their tight embrace. His voice reaches for the heavens in a solitary burst of coloratura. We have only a melodic line to judge by, but it radiates a kind of ecstasy.

And Beethoven left a clue to the kind of music that was on his mind. There is a phrase in the flute part, sketched over and over in slightly different ways, that stops just short of being a direct quote from Mozart’s “The Magic Flute.” It is the excited orchestral buildup just before Tamino, gazing enraptured at the likeness of a maiden he has never seen, sings, “Oh, if only I could find her!” Florestan, gazing at the likeness of a wife he is sure he will never see again, might have sung a lament. But this theme is charged instead with the jubilation of hopeful young love.

Mozart was never far from Beethoven’s thoughts as he confronted the opera stage for the first time. The parallel between Leonore’s big E major aria and Fiordiligi’s in “Così Fan Tutte” has long been noted, and it was a thrill to see another such link practically leaping off the pages of the sketchbook. There are also bits of melody that either hark back to the Adagio or look forward to the known conclusion. These helped too: I could at least get started by borrowing the harmony and orchestral figuration that goes with them. Bit by bit, the ideas piled up.

In the Adagio, several clues convinced me that the missing 1805 version was probably closer to the sketches than to the 1806 revision. That’s a guess — we can only ever guess — but the sketches have some dramatic gestures and a soaring final melody that Beethoven did not keep in the more serene versions of 1806 and ’14. Less resignation, more protest, more yearning.

From one sketch or another, it’s possible to assemble a near-complete draft of vocal and instrumental melody straight through the aria. The top line Opera Lafayette’s audiences will hear is at least 95% Beethoven. Inventing the missing orchestral score is another matter.

The process goes something like this: You first write down the notes Beethoven definitely used, from those surviving pages. Next, the ones you’re fairly certain about — in this case, a short quotation in the 1805 overture. Third, the melodic lines you’ve chosen from his sketches; you’re not sure they’re the ones he chose, but at least you know they’re his. Fourth, the ideas you’ve found by analogy with similar passages elsewhere, or in some other score you think Beethoven was hearing in his head. With each step of this sequence you’re getting farther from certainty, but you’re not yet exactly inventing.

When all that is done, though, you’re still staring at a lot of blank music paper. Except where you found one to borrow, there’s no bass line. Harmony and orchestration are up to you. You feel like an understudy subbing for a star in a rehearsal: It’s not your show, so there’s a certain appropriate caution, and yet whatever talent you have is going to be needed, so you had better let yourself go and do the best you can.

This is, of course, risky. You’re no Beethoven, to say the least. Somebody else might have picked better hints from his other pieces. But you have to take the risk. Beethoven had a clear idea of how this scene should play, and the only way to hear it is to fill in the blanks.

My contribution amounts to about 4 1/2 minutes, barely a third of what Franco Alfano provided for Puccini’s “Turandot.” But it was exciting to feel, for a little while, like Beethoven’s long-distance assistant. What I hope is that the result can at least allow his original concept of the aria — and some beautiful musical ideas — to speak again after more than two centuries of silence.

© 2020 The New York Times Company