Christoph Eschenbach leads the NSO in 2012. On Thursday night, they took on Mahler’s Ninth Symphony, presented less as a late Romantic work than an early modernist one. (JUANA. ARIAS/FOR THE WASHINGTON POST)

“Mahler Explored” is the rubric for the National Symphony Orchestra’s occasional visitations over this season of Gustav Mahler’s works. On Thursday night, Christoph Eschenbach and the orchestra probed the Ninth Symphony and found something that was, certainly, completely different.

Mahler wrote a lot of long symphonies, and a lot of weighty ones, and the Ninth still manages to stand out — among the longest (it lasted more than an hour and a half on Thursday) and probably the most poignant, filled with an intense, autumnal ache from beginning to end. That, at least, is how it usually sounds. It was, however, written in the 20th century — largely composed in 1909, it premiered in 1912, shortly after Mahler’s death — as the NSO’s program book took pains to remind the reader; one could infer that this emphasis was due to the fact that Eschenbach conducted it as an almost modernist piece.

As a conductor, Eschenbach is anything but detached. So it was particularly striking to hear the unsentimental objectivity with which he approached this work, from the very first bars of the first movement, usually lowering and pregnant with unshed tears, here almost clinical in their straightforwardness. It was slow, to be sure. It was very, very slow. In that slowness, the glue of the wonted romantic phrasing of the music started to dissolve, leaving notes adrift, instrumental voices sounding wholly independent of each other, snatches of melody emerging from a Babel of sound in which middle voices overwhelmed the ones that are usually dominant, and traditional hierarchies of melody and shaping were overthrown.

Eschenbach seemed more interested in the raw juxtaposition of sound, and even the collision of sound, than in the kind of burnished polish that is often given to this music. When two instruments intersected on a single note, he was not interested in smoothing it over, but in the slight dissonance of different timbres — a slightly strident flute, bisected by a shrill solo violin. He held out chords to emphasize tonal dissonances that a more romantic legato might ride over. It’s not that his interpretation lacked emotion: His emotional intensity was very much present. But it was an intensity of anarchy, of a sound-world drifting apart: the sound of music grasping at traditional connections precisely because they were already moving beyond the music’s reach.

The evening was dedicated to the memory of Edward Cabarga, a clarinetist with the orchestra since 2000 who died of cancer Sunday, at 53. It was a particularly fitting tribute to someone ripped early from life.

The symphony will be repeated Friday and Saturday at 8 p.m. The next “Mahler Explored” program will be on May 7, 8 and 9.