Music@Menlo 2008 has officially begun. On Friday night, Stuart Isacoff led the summer’s first Encounter, an enlightening discussion on the subject of temperament. Aided by a fascinating array of visual illustrations, performances by festival artists, and two Steinway grand pianos, side-by-side on the stage of Martin Family Hall and tuned to different temperaments, Stuart examined the development of—and history’s heated philosophical disputes over—the tuning of the modern piano. Indeed, the piano was the star of the evening: Friday’s Prelude Performance featured crack performances of the keyboard music of Bach by Chamber Music Institute pianists Qing Jiang and Liza Stepanova. The festival season promises much more great music to come, beginning with this evening’s Prelude Performance (6:00 p.m., FREE), which offers concerti by Corelli and Handel; and “Towards Bach” (8:00 p.m.), comprising masterworks from the early seventeenth century through the apex of Bach’s oeuvre.