Biss is 39 but has the gravitas and experience of an elder statesman — particularly when it comes to Beethoven. He has just completed a recording of the entire sonata cycle over nine years, accompanied by an online series on the Coursera platform called “Exploring Beethoven’s Piano Sonatas,” created with the Curtis Institute, where he studied and where he is now on the faculty. He studied with Leon Fleisher and thus is a grand-student, so to speak, of Artur Schnabel, the high priest of Beethoven in the 20th century and the first pianist to record the entire Beethoven sonata cycle.
Schnabel was also known for his imprecision — the “clinkers,” as he termed them — and on Sunday afternoon, it sounded as if Biss had picked up some of those along the way. You could hear the arc and intention of the ideas, but the tempos were mushy and the playing often soupy. The reason emerged at intermission: Biss was feeling ill but would try to finish the concert. He returned to the stage, his face grayish, and worked his way valiantly through the program, which opened with the expansive No. 4 in E-flat, offered the “Pathetique” (No. 8) as the most famous piece on the program, continued with the sunny and ingratiating No. 10 in G and ended with the ambitious and expansive No. 11 in B-flat (Op. 22), which Beethoven was very proud of but which hasn’t proved one of the more enduring sonatas, perhaps because he colored more within the lines in this piece than in many of the others.
It’s always interesting to hear what superb artists sound like when not at the top of their game — to get a look, in effect, at what lies behind the polished curtain, where the weaknesses are and what remains. And in a career that puts such a premium on perfection — to the extent that some Juilliard students fear that any audible mistake could cost them their future — it’s courageous to go out on a day that one knows probably won’t go well. Biss offered a vision of compelling musicmaking, of a gripping narrative sense, and even of some of the struggle that we associate with the deaf Beethoven’s pounding at the keys. But as a performance, it was more a placeholder, and a promise of what lies ahead — the middle- and late-period sonatas Biss will perform in the next two concerts, in December and March.