Thursday night at the Philadelphia Orchestra, the most powerful thing was the quietest. It actually didn’t involve the orchestra at all. Pianist Jonathan Biss had just played the Schumann Piano Concerto with the orchestra, and as a solo encore he chose another sliver of Schumann.

It was the last movement of the Kinderszenen (Scenes from Childhood), and Biss played it with such a sense of peace and elongated time that Verizon Hall suddenly seemed like the answer to a topsy-turvy existence.

On the page, this little Schumann piece doesn’t give up its secrets on first reading or the fiftieth — the technique required is so simple a child could play it — but Biss found in it something deeply stirring. He layered a sense of truth and sincerity onto a string of notes so profoundly felt that it changed what we can expect from the world around us. Or should.

The piece’s title: “The Poet Speaks.”

This is exactly why we come to artists. The concert was to have been shaped by another personality, that of Myung-Whun Chung, the South Korean conductor who last led the orchestra in 1996. But visa hurdles kept him from visiting, the orchestra announced 10 days ago.

Other, more familiar personalities stepped in, with Kensho Watanabe conducting the Friday afternoon concert and Yannick Nézet-Séguin taking Thursday and Saturday.

The standard-repertoire program stayed the same, and it points the way to next season, devoted largely to Beethoven.

Nézet-Séguin Thursday night weighed in with the Symphony No. 3, the “Eroica,” and it was hard to tell what exactly he thinks of this piece. If what we want from artists is a personal imprint, Nézet-Séguin didn’t deliver. The discernible features in the first movement were a somewhat flexible tempo, and making the drama — like the much-discussed clash of dissonant notes at one pivotal point — somewhat subdued. He did allow a bubbling up of emotion in the second movement, and he knows how to draw moments of sweetness from the strings. The horns shaped their trio in the third in ways noble and triumphant.

Nézet-Séguin heard the fourth movement as a chance to launch headlong from one section into the next, with his signature fast tempo suddenly boosted to a bat-out-of-hell level in the jumpy G minor variation.

He’s fun to watch, for sure, but for a fully formed interpretation one had to look to his handling of Weber’s Overture to Der Freischütz, which opened the concert. Here, especially in the beginning, was detailing to a fine degree — the Wagnerian broadness of the opening notes, the extremely quiet and beautifully textured response. The entire piece was a tight and powerful statement.

Pianist Jonathan Biss
Pianist Jonathan Biss

One of the benefits of having an artist like Biss around (he is a professor at the Curtis Institute and a Philadelphia Chamber Music Society regular) is eavesdropping on truths uncovered by his pursuit of a work’s character. He gets what makes Beethoven Beethoven, for instance, and his take on Schumann is no less sharp. If others try to smooth the composer’s jagged edges, Biss preserved and heightened them in the Piano Concerto in A Minor.

The impetuousness of the writing was all there, the panic attacks in the first movement and the quickened pulses of carefree release in the second. Biss is a big personality, but one whose opinions stem from the source: the composer.

The audience for much of the concerto took it upon itself to be participatory. I gave up counting first-movement coughs after the first 30 or so. The encore, though, quelled them. Even the sick and pollen-stricken tend to summon silent strength in the presence of a true poet.

Additional performances: Friday at 2 p.m. and Saturday at 8 p.m., Verizon Hall, Broad and Spruce Sts. Tickets are $10-$173., 215-893-1999.