After performing five selections from Book I of J.S. Bach's "The Well-Tempered Clavier" last evening in a lecture-recital at Catholic University's St. Vincent Chapel, pianist Alfonso Montecino explained that a keyboardist needs absolute emotional commitment to convey the moods behind the technical brilliance of each prelude and fugue. In his traversal of 10 pieces from Book I, Montecino combined expert execution with a keen interpretive insight to inaugurate this week's Bach festival and symposium.

Book I is a compendium of 24 preludes and fugues that explore all 12 of the major and minor keys. The preludes serve as e'tudes, exploring specific areas of technique, while the fugal portions, in their myriad forms and textures, represent the epitome of monothematic writing. Collectively, they are pedagogical and enlightening--the perfect functional art.

Montecino's sensitive playing, in turn, was both a history lesson and a rewarding aural experience. He showed the numerous shadings in temperament associated with individual keys, and how, in the hands of a composer such as Bach, contrapuntal lines can weave a wondrous sense of drama as they proceed to a predictably logical conclusion.

The opening and closing excerpts, No. 10 in E Minor and No. 24 in B Minor, were especially affective. The E Minor Prelude contains a lovely melody supported by a five-finger exercise for the left hand that Montecino delivered with a flowing grace. For the B Minor, containing a fugue that uses all 12 semitones of the scale, he brought power and panache, closing Bach's book in a manner befitting a volume that rewards with each new reading.