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There’s an extraordinary and unsettling passage in the second movement of Mozart’s Violin Sonata in B-flat (K.454). The music, which to this point has spent most of its time in a major key, shifts to the minor, and its character takes on an aura of gloom rare in Mozart’s output.
When the violinist Christian Tetzlaff and pianist Lars Vogt reached this passage in their Sunday recital at Jordan Hall, several things happened. Tetzlaff’s tone darkened substantially, the tempo slowed a bit, and he and Vogt expanded the dynamic range, so that each dissonance seemed like a cry of pain. When the music shifted back to the major, it was as though dawn had broken after a long night.