The idea that applause in response to performance should be spontaneous is a relatively new one. Roman emperors trained professionals to mingle with crowds at key moments, encouraging the dull roar of approval that speaks of a mandate. This behavior was refined in the theaters of 18th- and 19th-century France, where the term “claque” — from the phrase “to clap” — was coined.

At the Paris Opera, claqueurs became mighty arbiters of theatrical success; Balzac writes in “La Comédie Humaine” that the chief of the claque had “the endorsement of the boulevard playwrights, all of whom have an account with him, as they would with a banker.”

Mr. Abramov’s face is well known in the Moscow theater world, which is not surprising; he says he attends 300 shows a year at the Bolshoi. But the specifics of his operation — he calls it a “ministry” that he does out of love and fanaticism — are mysterious; Mr. Abramov has only given one previous interview, in 2004. The Bolshoi’s press secretary, Katerina Novikova, would not comment for this article, except to say that she regretted my choice of topic.

When I asked the Russian ballet critic and historian Pavel Gershenzon about Mr. Abramov, Mr. Gershenzon’s face took on a rapt expression.

“How does Roma get to the theater? I don’t know,” said Mr. Gershenzon, a former deputy director of the Mariinsky Theater in St. Petersburg. “I don’t know who he is. I don’t know where he lives,” he said in a tone of wonderment. “Is he a Jew?”

“I do not even know his last name,” he added.

Mr. Abramov describes his work as a well-codified transaction: The claque provides artists with a guarantee of applause, and in return it receives free passes allocated to artists, usually two in the stalls and four to six passes to the circle or dress-circle. Because the modern-day claque represents multiple artists appearing in the same show, Mr. Abramov can often secure up to 28 seats in the theater on a given night, a remarkable fact given that tickets for a performance of “Swan Lake” sell for somewhere between $300 and $500.