Unlike the music of Christmas or Easter, the music of Thanksgiving is harder to pinpoint. Shuffling leaves? The drum-brush strokes of a knife carving the turkey? Vince Guaraldi, an early lead-up to Christmas through the dim or vivid Charlie Brown television-memories of readers of a certain age? An uncertain business, but here are a couple of thoughts. First, when in doubt, start in the seventeenth century. The “Te Deum & Jubilate for Voices and Instruments made for St. Cecilia’s Day 1694” of Henry Purcell was apparently performed as a Thanksgiving piece, as noted by Michael Evans Kinney and the Stanford libraries: While not much is known about the early St.…