(L to R) Alex Dobson, Blandine Staskiewicz, Pascale Beaudin and Antonio Figueroa in rehearsal of Opera Lafayette's production of Mozart's “Cosi fan tutte.” (Louis Forget)

There is an ignorant smugness to posterity. We who love the art of the past tend to assume that works that have survived for centuries are the best representatives of their time. In fact, the works we love today were often the exceptions. “Too many notes,” the Emperor Joseph II allegedly said of Mozart’s “Abduction from the Seraglio,” while contemporary reviewers puzzled over Beethoven’s latest piano sonatas, deeming them decidedly too challenging for most players (they weren’t wrong). The works that were the most popular and beloved in their day are, most often, quickly forgotten. Such works have become a mainstay of Opera Lafayette.

Opera Lafayette is a homegrown Washington company, literally: It began in the basement of Ryan Brown’s house on Capitol Hill in 1994. Its focus is French opera — originally French baroque opera, but, like many early-music groups, it has ventured ever further afield, all the way into the 19th century. One of its specialties is finding connections between works we know well and works we don’t know at all. In 2008, it presented an evening of antecedents to Mozart’s “Don Giovanni,” a reminder that Mozart and Da Ponte drew heavily on contemporary sources. In 2012, it offered “Barber of Seville” — not Rossini’s, but Paisiello’s. On Friday, at the Kennedy Center’s Terrace Theater, it is offering the second part of its ambitious “Cosi fan tutte” project, which pairs Mozart’s opera — abridged, sung in French, with spoken recitatives — with a work by François-André Danican Philidor, “Les femmes vengées,” which, like many of the works Opera Lafayette has presented over the last 20 years, you’ve almost surely never heard of.

“I look at a lot of scores on my piano of all these various not-so-well-known composers of the 18th century,” Brown said in a phone interview last week. “I try to find a way in: What’s interesting about this one?” In the case of “Les femmes vengées,” the parallels to “Cosi” leaped out: Both operas feature six characters, in three pairs, in various romantic entanglements. Opera Lafayette’s conceit is to offer the Philidor as a sequel to “Cosi,” set 10 years later, with all the couples more or less happily married — including Despina, the maid, for whom the company introduced a non-speaking male role in “Cosi” for the purposes of pairing her off at the end of the show.

Philidor was one of the leading composers of his day, though he is better remembered now as a chess player. Opera Lafayette exhumed his light, humorous “Sancho Panca” opera in 2010, and is following up with “Les femmes vengées,” but even Brown is not making great claims for these works as unheralded masterpieces. “My line is that it’s dessert after a sumptuous meal,” he said of the “Cosi”-Philidor pairing. “Of course it’s lighter, but when you hear it, would you have it be anything else?” He adds: “The Philidor [is] more dialogue-heavy and music-light. The dialogue is actually in verse, too. You have to make sure it doesn’t sound like Dr. Seuss.”

You can’t accuse Brown of lacking ambition. Opera Lafayette began as an early-music orchestra, the Violins of Lafayette, and moved on to offering opera in concert performances. These days, in addition to seasons of two or three productions, it releases albums at a rate of about one a year on a series for the label Naxos that has won the company considerable acclaim. It brings one production a year to New York, where it will offer “Cosi” and “Les femmes vengées” as a double bill for the first time — no longer as a concert opera but, as has been Opera Lafayette’s practice for a couple of seasons now, in a fully staged production. It will then take the show on the road for the company’s second appearance in the Opéra Royal of Versailles, France.

And that’s just warming up for its 20th-anniversary season in 2014-15, which coincides with the 250th anniversary of the death of Jean-Philippe Rameau. Opera Lafayette will mark both anniversaries with another modern premiere: the opera-ballet “Les fêtes de l’hymene et de l’amour,” a spectacular work written for the marriage of the Dauphin in 1747 that involves soloists, orchestra, chorus and no fewer than seven ballets, which Opera Lafayette will present with three different dance companies in the Kennedy Center Concert Hall. It’s a big venue for a company that usually performs in the much smaller Terrace Theater, but Opera Lafayette has been there before. For its 15th anniversary, with Gluck’s “Armide,” it managed to sell the concert hall completely out.

“The big white elephant in the room is the cost,” Brown said, “because it’s generally exponentially more” expensive to present staged opera, to say nothing of the costs of recording the albums. “We have built up over the years a substantial reserve fund, which has given us the comfort to do this, but facing this year and next having committed to these stage things is daunting. We’re very much hoping that doing staged opera will bring in more board members, as well as audience.” So far, he seems to be doing something right: The company has weathered the financial turbulence of recent years with a slowly but steadily growing staff and budget. This year, Brown said, the annual operating costs went above $1 million for the first time.

French baroque opera in a small market would seem to be a relatively narrow foundation on which to build such a solid success. One reason Brown has done well is that he hasn’t limited himself. Exploring little-known 18th-century opera led him to the roots of the genre of opera-comique, such as Monsigny’s “Le roi et le fermier,” which was the company’s first production at Versailles. It took a lot of nerve for an American company to come to France to perform a French opera in the theater where Marie Antoinette often had it played, a couple of decades after its 1762 premiere. It took all the more nerve given that it was Opera Lafayette’s first-ever complete opera staging. Serendipitously, the staff at Versailles found the original 18th-century sets. The performance went so well that it promptly led to a repeat invitation.

Meanwhile, Brown continued his opera-comique exploration with the modern premiere of another work that was wildly popular in its day and forgotten in our own: “Lalla Roukh,” by Felicien David, first performed in 1862. Opera Lafayette has pushed the release of its “Lalla Roukh” recording to coincide with a big David retrospective in Europe this spring; Brown hopes to take the work on tour.

“The operas-comiques have smaller orchestras and smaller casts. For our upstart American company, it’s fortuitous that it was a gap to fill in the recorded [legacy], adding to the canon and the understanding of musical influences at the time.”

“I think he has an affinity for that style,” said Catherine Turocy, the founder of the New York Baroque Dance Company, speaking of Brown’s work with 19th-century opera. Some conductors tend to look down on popular art, but “when Ryan looks at it,” Turocy said, “he sees connections with more serious pieces, sees it in a cultural context and is able to appreciate its popularity.” Turocy, who met Brown years ago in New York when he was a violinist in the Concert Royal, an early-music orchestra founded by her husband, James Richman, has frequently choreographed, directed and even, at the beginning, mentored Opera Lafayette’s productions. “I actually said, ‘Don’t put on a production; do a recording first,’ ” she said. “Put your money in recording the music rather than putting on a huge opera, because it will help build a fan base.” It was astute advice. “These days,” Turocy said, “I’m perhaps more emotional support — just clapping.”

Opera Lafayette’s 20th-anniversary season next year will include two fully staged operas. “You can’t really go back,” Brown said. He’s already looking ahead to even more ambitious ventures. “I’d love to do a ‘Fidelio’ project,” he said, with “the French opera by Gaveaux [written in 1798] that the libretto Beethoven used is based on. I’d love to do both the Gaveaux and the Beethoven.” He conceded, “That’s getting hugely ambitious.” Beethoven’s sole opera requires huge orchestral and vocal forces beyond anything Opera Lafayette has yet fielded. “But if you don’t dream. . . .” The rest is self-explanatory. In any case, Brown has to go oversee a keyboard tuner before his next rehearsal.

Opera Lafayette presents ‘Les femmes vengées’

Friday at the Kennedy Center’s Terrace Theater, Jan. 23 at Lincoln Center’s Rose Theater in New York, and Feb. 1 and 2 at the Opéra Royal in Versailles, France.