Appraiser Brendan Ryan was at a house in Greenwich, Conn., to take a look at furniture and other items the owner wanted to sell, but it was a framed document hanging on a wall that caught his attention.

"I said to myself, 'Oh my God, that's Beethoven," Ryan tells ABC News. Beethoven's handwriting is "unmistakable," explains Ryan, who is also a composer. His hunch panned out, and what turned out to be a rare 1810 Beethoven sketch leaf of Beethoven's opus 117, König Stephan, sold at auction in November for $120,000, the Journal News reports.

But before that could happen, the sketch leaf had to be authenticated and the music identified, and Ryan is providing new details about the weeks-long process.

“I equate it to trying to find a word in the dictionary without knowing the first letter," says Ryan, who sought the help of his former music professor, Mel Comberiati of Manhattanville College in Purchase, NY. The pair pored over the digital archives of Beethoven's works from the Beethoven Haus in Bonn, Germany. Most composers threw out their notes, but luckily, "Beethoven didn’t throw anything out," Comberiati told Greenwich Time. One important clue came in the form of three small holes on the side of the leaf that matched up perfectly with known samples from the complete sketchbook. The sketch leaf sheds light on Beethoven's process, showing ideas in pencil getting tweaked and then made permanent with ink, reports ABC News. "It's kind of a mess," Comberiati tells the Journal News. "He's working out the music.

He writes a line, crosses it out." It's like the "moment you get to see inside the composer's mind." (Beethoven's heart arrhythmia may have influenced his music.)

This article originally appeared on Newser: Beethoven Sleuths: Old Sheet Shows How He Worked

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