Although he composed in many musical genres, Vivaldi truly redefined the concerto and made it distinctly his own. And although adept at writing for a variety of instruments, the violin remained his primary instrument. The composer's 12 concertos known as "L'estro armonico" [Harmonic Innovation] are distinguished from all other ensemble music of their time by their emphasis on virtuosity, their rhythmic exuberance, flexible instrumentation, independent...