The aura of seeming effortlessness around Johann Sebastian Bach's craft sometimes obscures that the Baroque was a time of aesthetic extremes. Some of that can be sensed in the contrast between the era's most prominent keyboard instruments: the harpsichord's unavoidable decay, the organ's unflagging sustain. (Tellingly, the piano, mediating between those poles, only gained traction as the era wound down.) On Saturday, at the First Lutheran Church, Luca Guglielmi used Bach's music to navigate those two instruments' divergent interpretive and technical claims.
The concert — presented by the Boston Early Music Festival — was organized as two imaginary recitals, Guglielmi's conception of how Bach might have shown off each instrument. On the harpsichord — each note quickly evaporating, with only the variation in volume between two manuals to work with — Guglielmi alternately avoided or emphasized concurrence to make musical points. In the Suite in C minor (BWV 997, better known today in its version for lute), Guglielmi's playing was all rolls and breaks, notes nudged into the spotlight by being knocked slightly off the beat; the whole undulated like a loose cat's-cradle of melodic lines.