For pianists, Beethoven's 32 sonatas are "Mount Everest." Or perhaps "the Rosetta Stone." Or even "The New Testament."
Garrick Ohlsson will play the entire cycle in a series of eight concerts this summer.
"They represent a lifetime of preoccupation with both a form and an instrument, in which you can read the full development of Beethoven," he says.
The sonatas were Beethoven's laboratory. The piano was his instrument. It was in these pieces that he composed and performed his musical ideas, many of which later found their way into his chamber and orchestral works.
He began them in the 1790s, while still under the influence of Haydn and Mozart. Then came his Romantic awakening, which he poured into some of the sonatas of the early 1800s.
Finally there were the works that Ohlsson says "helped change the course of musical language for the next hundred years, emotionally and spiritually."
Take No. 29, for example: The Hammerklavier Sonata.
Robert Taub, who wrote a whole book about the sonatas, calls it "the sonata that makes all of us pianists quake in our boots."
"It's this wild fugue, jumping all over the place," Ohlsson says. "The music gets so furious and so wild and so extreme, and is pushing the boundaries everywhere ... it's just hard to keep your head cool enough to play it."
"There is a huge struggle in his music," says Mitsuko Uchida, who has recorded the final three sonatas for a new CD. "And I struggle with him."
The struggle is obvious to those who have studied the manuscripts.
Taub found "evidence of his own tears on the page. Smearing, in particular with one of the late string quartets. You can see wine stains from when he brought sketchbooks into taverns. You can see wax candles burning as he crafted his musical offerings to the world."
And the sheer force of Beethoven's work, Taub says, drove piano manufacturers to improve their product: "They were forced to create instruments that could withstand his playing."
By the time the last three sonatas arrived in the 1820s, the word "innovation" seems inadequate to describe what the composer had accomplished. He had transformed the sonata, the instrument and music in general ... in the face of his growing deafness.
"When you are stuck in hell, you look up; he makes you look up," Uchida says. "And there is heaven, a glimpse of it. And that unbelievable optimistic spirituality is so gripping."
"The titanic scowling genius, shaking his fist at the stormy heavens," Ohlsson says of Opus 111, the final sonata. "Raging against an unjust and cruel and a really terrible fate in his deafness and his illness ... he transcends it ... going from darkness to light. You reach a place of serenity that is almost unique in the whole of musical art."
Sara Fishko is a reporter for WNYC in New York City.