LUIGI Nono's elongated string quartet entitled Music of Silence was not exactly the joker in MusicaItalia's pack of modern Italian cards at the weekend, though it differed from all the others in its total reliance on the plink-plank-pause method of composition still prevalent at the time it was completed in 1980.

Today Nono's music can sound serious to the point of sterility. Yet as the product of one of Venice's most fastidious musical minds, it continues to make its effect in a performance as assured and as keenly defined as the one given on Sunday by the superb young Quartetto Borciani at the Scottish National Gallery of Modern Art.

Austerely inspired by the poetry of Holderlin, the work was in essence a song cycle without the songs. Where you expected to hear words, you encountered only moments of silence where the players were instructed to ''sing'' the poetry mentally to themselves. For the composer, the result represented songs ''from other spaces, other skies'', but for the listener - this listener - Nono's meticulously timed poetic vision proved harder to come to terms with.

Yet the feat of sustaining such sparsity for up to 45 minutes but with constant attention to delicate sonority, was something to marvel at. In the minimalist decor of the gallery's gymnasium - the building was originally a school - it found its perfect setting. The music may have been a challenge to patience, but it was also a challenge to the faculty of listening, wherein perhaps lay its raison d'etre.