The guitar is the popular instrument par excellence. As apt for Brazilian sambas for Irish ballads or American blues, the guitar has also recently been adapted as a surrogate for plucked instruments from non-Western musical traditions; no idiom seems beyond its reach. When social history of the second half of the twentieth century is written, it may be seen that the guitar is as central to this era as the piano was to the nineteenth century. But while the piano was an emblem of upward social asp…