Scarcely a week goes by without our hearing about some ten-year-old boy or girl in Tokyo, Moscow, Seoul, Shanghai or Tbilisi who is rendering technically flawless performances of some of the Fafnirs of the repertory. In 1997. I heard one of these miraculous children for the first time:  A 14-year-old boy gave the solo piano part in Beethoven’s “Choral Fantasy” a traversal equal to those of Sviatoslav Richter, Martha Argerich and Evgeny Kissin. I predicted a great future for him.Two years later, he was world famous; ten years after that, he was listed by Time magazine as one of the 100 most influential people on earth. And he’s perhaps even more famous now then he was then. Friday evening in Symphony Hall, the now 42-year-old pianist made his seventh appearance in this city’s Celebrity Series.Robert Torrres photoFor most of his career, he has been a controversial figure. The precocious teenager I heard play in 1997 long ago became the most shameless mugger in the classical-music world. Compared to Lang Lang, Yo Yo Ma is a poker-faced Buster Keaton.For almost all of Friday evening’s program, all of the emotion coming from the stage seemed to originate in the pianist’s sweeping and swooning mannerisms; unfortunately those gestures did not translate into projected emotion. Faure’s Pavane, like all his writing for piano, is filled with grace and insouciance and moves with a tread that has been compared to that of a cat ― but one without claws. It is filled with emotion, but emotions that are subtle. Lang Lang played it in a manner that can only be described as heavy handed; hardly with catlike tread. To my ears in row N, it powered forth with volume stretched far beyond the composer’s Gallic restraint.Schumann’s Kreisleriana, Opus 16 is one of the composer’s greatest works: eight pieces that are drenched in fantasy and whose effect can be compared to that of a hypnotic dream. Like all of the composer’s output it’s filled with temperamental contrasts. The trick to interpreting Schumann is to unify its magnificent diversity into a coherent narrative. The music cannot be overpowered, and it requires the widest of tonal palettes. But overpowering the music is what Lang Lang tried to do, although it also must be admitted that the filling a sold-out Symphony Hall with the sound of a single piano requires a very outgoing personality. From where I sat, the playing was sometimes so loud, it drowned out the music; occasionally so slow that the line broke; and at other times too fast to contemplate. Yes, there were lots of stops and starts, extremes of rubato, and abrupt if sometimes reasonable changes in dynamics, but none of those expressive devices ever felt earnest or anything other than predictable. The over-plenteous nuances resembled a paint-by-numbers canvas with too many pigments. Kreisleriana’s affect is of a remembered nightmare, not a pianistic hard sell.Chopin’s 60 mazurkas are among the most difficult works in the pianist’s standard repertory. Very few resemble each other, except that they all require a delicacy of expression that is forbidding and a flexibility of rhythm more intimidating still. Opus 17, No. 4 in A Minor, opens with wonderful and subtle dissonances that introduce one of Chopin’s most touching themes and then returns at the end and dissolves into silence. It is a magical moment, but in Lang Lang’s performance nothing magical happened. As in the Schumann, almost every phrase sounded like an invitation to look at him. But by the final mazurka, Opus 59, No. 3 in F-sharp Minor, the heavens began to open up.  As Susan Halpern made clear in a fine program note, this piece “is richly varied and noble … both innovative and profound and feels at times like a waltz, at times like a polonaise.” Lang Lang made one unusually aware of these qualities and put across the extended, dramatic coda with an impressive sense of closure. This was the most rewarding interpretation of the evening.So, I was not completely surprised by the concluding number – the F-sharp Minor Polonaise. There has never been any question about Lang Lang’s ability to play the instrument and the F-sharp Minor Polonaise has bravura octave passages that make it a paradise for any virtuoso with Lang Lang’s equipment. But he finally generated more than mere excitement. We were now witnessing some deep understanding and engagement. Like the mazurka before it, this polonaise expanded the genre. The middle section is a mazurka, thus creating an intensity which derives from the instability inherent in what the pianist John Ogdon called “a remarkable coalescence of two different dances.” Ogdon wrote of its “Goya-like intensity” and depiction of “almost inhuman barbarism.”Of all the works in the Chopin canon, it’s the one in which the composer’s expression of emotion is the least filtered. His anger as a Pole about the crimes committed by Russia upon his homeland was probably similar to what Ukrainians feel today.Finally Lang Lang was dispensing real musical gifts.His encored first with the quiet, introspective, and rather pointless fourth of Charlotte Sohy’s Pieces romantique. Then he ignited Manuel de Falla’s Ritual Fire Dance to the sold-out hall with sweeping arm gestures, choreographed interlocking trills, and irrepressible bravura.Stephen Wigler has a peculiarly geekish interest in the piano and in pianists. He has served over the years as a staff music critic in Orlando and Baltimore.