Italian composer Aldo Clementi (1925-2011) created using rigorous methods. Most of his works include canon (strict imitation) in a number of different ways. Clementi’s music is reserved and enigmatic in style, suggesting musical structure without being obvious.

One entrance to this difficult work is unaccompanied renaissance choral music. Otto frammenti (1978-97) is based on the 15th-century French folk song, L’homme armé, the cantus firmus (structural voice) of many renaissance masses and motets. Each fragment in the work uses a section of L’homme armé. The string quartet members play without vibrato suggesting the sound of viols. I find the effect mystical; even more so is Momento (2005), which draws me into sustained attentiveness to still intervals and chords in a sparse tonal landscape. Long consonant fifths and thirds glint out and shine, and the perfect fifth (that strings tune to) seems iconic for Clementi. The composer’s journey was a long one. By contrast, the much earlier, more chromatic Reticolo: 4 (1968) has a quick steady pulse involving both pizzicato and bowed notes that set up unexpected jazzy syncopations.

The Montréal-based Quatuor Bozzini are ideal interpreters of Clementi’s music. For example, in Satz 2 (2001) their mastery of intricate non-vibrato and sul ponticello (near the bridge) effects is striking. Champions of new music performance at a high level, with an international reputation and their own Collection QB recording label, this is an ensemble well worth experiencing.

More desiccated modernism by Quattor Bozzini as they perform Momento (CQB 1615) by the depressing post-serialist Aldo Clementi. This Italian composer who died in 2011 seems to have regarded his work in purely academic terms, measuring his success as a series of “contrapuntal exercises”; critics, when attempting to summarise it, apparently tend to reach for metaphors of decay. Clementi strove to compose music that describes its own gradual extinction. One imagines he was happiest when watching the sands run out of an hourglass, and then retiring to bed replete with the satisfaction that another day had been wasted. These various canons and other pieces, ranging in date from 1968 to 2005, brought a deathly pallor to my skin, induced short breathing, and made me dream of wandering 19th-century parlours with no windows and heavy green wallpaper everywhere.

The press release for Quatuor Bozzini’s new Aldo Clementi portrait disc alludes, in the form of a quote from the composer, to a peculiar sort of metamusical morbidity that was allegedly integral to his thinking. While his eldritch outlook is documented elsewhere as well, what is transmitted more clearly through this typically lucid Bozzini recording is an eccentric vitality.

Contextualizing Clementi amidst other parallel composers is no simple task. A common trait of many twentieth-century works is that the music itself, by virtue of its compositional language, tends to instruct its audience in how to listen to it. Clementi’s music, on the other hand seems reticent to guide listeners toward its particular features — even its own flatness of perspective. It neither bombards the listener with stimuli, nor is precious about detail; yet all the while it’s exceedingly subtle and frequently rife with ideas. Its harmonic world is often tight and chromatic, but it’s devoid of the expressionist narrative gravity that suffused the work of many of Clementi’s contemporaries.

Reticolo (1968) offers different strata of interlocking activity that are woven closely together in a manner that obfuscates change, yet produces sufficient energy to drive the work’s full eight minutes. The most recent work on the disc, the eighteen-minute Momento (2005), carries a similar effect of folding in upon itself. Framed in a more luminous harmony, it operates from a slow, continuous base. This texture is periodically both thinned out into single instrumental voices and punctuated with accents. Over its course it reveals material that paradoxically feels as though it’s constantly changing, while remaining perpetually familiar. Eventually, this obscure process is channelled through a more sibilant timbre, saturated with odd, overtone-rich lustre.

Knowing Quatuor Bozzini’s repertoire, one can understand their attraction to Clementi’s singular vision. Their investment is palpable on this recording, and their impeccably clear, mostly vibratoless inflection flatters Clementi’s remote yet generous work.

To say Aldo Clementi uses canons, is like saying Wagner wrote operas or that Beethoven was good at variations. Clementi’s elegant constructions use all manner of repetitions at different speeds and intervals. It may be hard at first to catch the structure because of the alternately knotty and playful tapestries, so well does Clementi’s music deliver mesmerizing events. Some pieces are long; the wintry Momento is 18 minutes, whereas we get two versions of the flowering Canone which takes about 75 to 80 seconds per pass. These extracts from Otto frammenti last 22-and-a-half minutes and contain a contradictory subtitle, “canoni 1-8, 33-40,” which suggests that the eight fragments are repeated or perhaps that they embed a subset. In fact, the entire work rich in palindromes explores the possibilities of the 15th-century tune L’homme armé.

The slipcase provides this telling artistic statement: “It has been my conviction for a number of years that Music (and Art in general) must simply assume the humble task of describing its own end, or at any rate its gradual extinction.” Imagine music boxes winding down after an intricately designed maximal moment. Taken together, this quartet program is powerfully autumnal. The Bozzini’s superbly blended colors have been mentioned before, and here they create galaxies that wobble before receding.