The first half of the concert, “Divisions,” by A Far Cry at Jordan Hall on September 23, which opened its fifth season, featured the unconducted string orchestra divided into varying combinations of instruments, but rather than heightening the differences, the separations served rather to underline a philosophical principle, that differences and divisions are ultimately only superficial, that all parts join together to make a whole, sometimes of shattering beauty.

Aarvo Part’s Fratres, superficially simple, starts softly, states a melodic fragment, grows louder, grows softer again until it almost vanishes. Yet, the juxtaposition of percussive punctuation (a bass drum and wood blocks), like a grand heartbeat, alternating with silence, and increasingly impassioned statements of the melodic fragment, all over a constant drone, creates a sense of movement, though whether it is the ensemble that is moving towards us, or we who are passing a constant and timeless play of music is impossible to tell. Karl Doty must be singled out for his beautiful control on the bass drone. His bow changing was so imperceptible that it created a sense of timelessness from which the rest of the piece flowed.

Vaughan Williams’s Fantasia on a Theme of Thomas Tallis featuring two separated string ensembles plus a solo quartet. This familiar work was played at a slightly brisk tempo, but the music’s rich lushness did not in any way suffer from this. The inner voices in particular were clearly heard, adding texture where sometimes one can be just overwhelmed by sound. The overall sense was of a kaleidoscope of string colors, folding, melting into each other, or the blossoming of a flower in fast motion photography. The piece was dedicated to the hoped-for recovery of a colleague who suffered a serious car accident this past summer, so perhaps the extra emotion lent urgency to the performance.

Steve Reich stated that he took his inspiration for the Triple Quartet from the fourth movement of Bartok’s Fourth Quartet. This performance featured two quartets in a straight line across the back of the stage and a third quartet in front in a more standard quartet seating. The players dove into this challenging work with frenetic energy. Its driving rhythm, stereophonic fragmentation of motives, and sometimes singing lines did convey a sense of Bartok, had he lived into the late 20th century and written a somewhat minimalist piece. One also sensed that there would be little help if by unlucky chance you lost your place in the music. But these musicians gave their all, and it was an energizing performance to watch and hear.

The second half of the program featured two fugal works, the Contrapunctus XIV from the Art of the Fugue, BWV 1080, and Beethoven’s Grosse Fugue, Op. 133. The ensemble made the interesting decision to play these two works attaca. Just as the Bach was petering out in the B-A-C-H theme that he left unfinished, they leapt into the Beethoven. In this half of the program, the violins seemed slightly more strident. It could be that the lower strings were so powerful that a larger violin choir could have balanced the sound better, or that the energy from the Reich had not yet worn off. But even at less than perfect, this ensemble’s energy is dynamic, and musically rewarding from one of Boston’s interesting and compelling ensembles.

Elisa Birdseye, executive director of the Boston Chamber Ensemble, is an active freelance violist and principal violist of the New Bedford Symphony. Additionally, she has worked as the general manager of the New England Philharmonic and Boston Musica Viva.