Bearing an exotically enigmatic title – Nu.Mu.Zu – the new work by the 80-year-old Georgian composer Giya Kancheli left a distinctly memorable impression in its North American première by the Seattle Symphony Orchestra under Ludovic Morlot. The world première took place only a few weeks ago in Brussels (Kancheli's current residence is in Antwerp), with Andrey Boreyko and the National Orchestra of Belgium; both that ensemble and the SSO co-commissioned the piece.

I admit approaching this new score with some scepticism, as I was baffled by the rapturous response to his choral-orchestral Styx, the previous Kancheli composition performed here, in 2013, with Boreyko guest conducting. For this listener, Styx seems wilfully naive, heavy-handedly theatrical, its hyper-romantic gestures veering perilously close to kitsch. But Nu.Mu.Zu – ancient Sumerian for “I don't know”, according to the composer – is a compelling orchestral essay that manages to move rather than manipulate, evoking powerful emotional responses through a deceptively simple vocabulary.

Kancheli pointedly weaves the thematic and harmonic substance he works with from references to the musical past: in particular, the chromatically unsettled theme of the E minor Fugue from Book I of Bach's Well-Tempered Clavier, which unspools in surreal slow motion at the start and recurs in various formulations. Kancheli's highly dramatic dynamic contrasts and isolation of particular sonorities require a Webern-like concentration from the musicians. These pointillist gestures, ethereal or aching – yet somehow at a dreamlike remove – alternate with massive, brutalist tutti outbursts.

Along the way, we hear fragmented tropes of an Eroica-ish funeral march, the sighs of Baroque grief (with an implied phrase from the so-called Albinoni Adagio in G minor), cadential trills that can never be resolved. But these aren't ironic postmodern deconstructions.  Nu.Mu.Zu purposefully never develops: it portrays a consciousness that can only musically retrospect or break down.

Morlot masterfully traced this arc, drawing out the eerie pauses Kancheli plants like landmines in his soundscape. A furious final outburst cuts off, with an effect similar to that of the abrupt end of The Beatles' “I Want You (She's So Heavy)”. And then the recurrent Bacchian strain seals it all with its doleful, hallucinatory refrain.

“Illusions that I knew something gradually disappeared and it turned out that having approached the age of 80 and lived a life full of contradictions I found myself utterly confused,” says the composer. “What is happening in the world is gradually, step by step, destroying the last hope in my consciousness, without which, for all of us, life loses its meaning. "I don't know" what will happen in the future. However, having lost hope, I keep dreaming about a world in which fanaticism, sectarian strife, and violence are no longer the dominant features of world order.”

Characteristically, Morlot's programming choice intensified the impact of the Kancheli by positing a thought-provoking contrast. The concert began with Bohuslav Martinů's Symphony no. 4, composed in the United States in 1945. In contrast to the world historical gloom of Nu.Mu.Zu, the Czech composer's symphony finds reassurance in musical tradition, and in the classical heritage specifically. Yet this is no simplistic 'war symphony'. Morlot's account revealed the surprising, at times contradictory emotional spectrum underlying the apparent journey towards concluding 'victory' in the final movement.

The conductor has shown a special affinity for Martinů (whose Oboe Concerto he included on his very first concert guest conducting the SSO), and Morlot was especially attentive to the menacing currents of mania that resurface through the course of the Fourth, as in the coda of the first movement. With the full-on tragic rhetoric of the Largo eloquently spelled out, this interpretation suggested a counter to the ensuing Kancheli: the tropes of the past can point a way through even the darkest times.

After intermission came a performance of Brahms' beloved Violin Concerto that was somehow less satisfying after the intriguing pair of the first half, despite the riveting and passionate contributions from Renaud Capuçon as the soloist. The French violin virtuoso played up the contrast between Brahms's more dramatic passages, with almost aggressively energetic phrasing, and the music's warm, lyrical glow, topping his rich sound with a honeyed legato.

Morlot found Mozartean felicity in the wind music opening the Adagio, but there was too much routine in the expansive first movement, which was adequate but not really exciting. It took until the unusual spirited finale for the Brahms to catch fire, with much interesting and original phrasing from Capuçon and the orchestra.