Like so much else in modern life, modern musical instruments have been designed to be assertive. By contrast, their Baroque forebears were geared to an ideal of ensemble and cooperation. Each one had a role to play and this was understood and accepted by everyone.

The Aulos Ensemble, a group of six musicians that performed at the Libarary of Congress Friday night, reflected this sound ideal and sense of interdependence splendidly. In a program of sonatas and concertos by Bach, Handel and Scarlatti, all of whom are being tricentenially celebrated this year, each musician declared and established a musical and an institutional personality.

The corporate foundation was represented by the continuo players, harpsichordist Charles Sherman and cellist Myron Lutzke, who together provided sensitive and sturdy foundations for all that transpired. Viola da gambist Richard Taruskin and oboist Marc Schachman were the ensemble's poets, projecting a sense of lilt and phrase with every line. And violinist Linda Quan and flutist Ann Briggs were the group's athletes, dancing through the music with less emotional involvement than the poets but with a marvelous sense of motion and inevitability.

On this particular program Bach clearly held the upper hand. Two of the works noted as attributed to Handel were, if really his, certainly early and not vintage material, and the Scarlatti, while delightfully mannered, seemed somewhat superficial in that company.

The performances were exemplary and the one thing lacking that night have added more sparkle to the occasion was some more daring harpsichord ornamentation.