There's a Bach Festival effect, and it has to be recognized. Seeing a church filled to the rafters with organ music, after an equally sold-out concert by Ensemble Masques the day before, and a week earlier, a sold-out harpsichord recital by Luc Beauséjour at Chapelle Notre-Dame-de-Bon-Secours: all this is more than remarkable, because it's truly tangible.