Boston Classical Review

Renowned for its proficiency with classical masters, the quartet, welcomed to Boston’s Celebrity Series on Saturday, was formed thirty years ago, when its musicians met while playing in Concentus Musicus Wien, an ensemble that pioneered the use of period instruments. Once formed, Quatuor Mosaïques followed suit and opted for gut strings.

Their sound, as a result, is unique. Gut creates more overtones than wire, and the sound has a soft edge. The ensemble also blends more easily into a plush fabric of sound.

What also distinguishes Quatuor Mosaïques is the musicians’ interpretations. The players spin phrases in long arcs, and their tasteful rubato shading breathed additional life into the Haydn and Mozart works they performed.

Though cast in C major, Haydn’s Op. 20, No. 2 Quartet is rife with storm and stress. The opening movement flowed from a singing cello melody, played radiantly by Christophe Coin, to passages of turbulence. In the Adagio, the stark unison phrase tilted the music toward darkness. The Minuet glided smoothly. But in the final movement, the musicians dug into their instruments for a grainy, agitated conclusion. This was a Haydn of drama and depth.

Their performance of Mozart’s Quartet in D minor, K. 421 was similarly stirring in its intensity. The first movement ran the gamut from shade to light and back again, the players shaping the phrases with a wide range of dynamics. In the second movement they mined the songlike grace from the music’s stormy exterior. Some of Mozart’s Minuets foreshadow the Scherzos to come in Beethoven’s music, and here the quartet played with a slight edge to the sound — a colorful contrast from the folk-flavored Trio. The theme of the second movement returns in the finale as the basis for a set of variations, and there the music danced.

Mozart’s Quartet in B-flat major, K. 458 provided a lyrical opening to the concert. Nicknamed “The Hunt” for its horn-like motives and the galloping figures in the first movement, it is one of the more familiar of Mozart’s Haydn Quartets — works he dedicated to the elder composer.

In the hands of Quatuor Mosaïques, the piece resonated with warm, singing lines. The Minuet had a smooth flow, more song than dance. And the Adagio glowed with a rosy timbre. Phrasing, here too, was sensitive, and Erich Höbarth’s long violin line passed gracefully to Coin’s cello. The outer movements moved with gentle rubato and finesse. Tone colors shifted like light through a prism for effects that were both bright and shimmering. It was, as Haydn himself put it, a true conversation among friends.