During the nineteenth century, bands and organs were the tireless spokesmen for operatic music composed for the theater. The phenomenon was both cultural and social since the need for opera, which was felt at every level of Italian society in the1800s, was nourished and sustained by various factors. First and foremost, obviously, came the artistic and musical aspects, but these were closely followed by the star system of singers and actors, and, finally, by a healthy dose of political propaganda which coincided with the establishment and consolidation of national unity (consider the roles played by Nabucco, in full Risorgimento, and thirty years later by Aida, as typical examples of “national opera”). In light of the influence that opera had on organ practice, it is worthwhile to observe the phenomenon from two different–albeit complementary–points of view: those of organology and organ performance. In the minds of organ builders, the capability of playing arias, cabalettas or overtures on the organ signified building instruments which could faithfully realize the various unique characteristics of operatic language: the greatest possible contrast and diversification between melody and accompaniment, faithful imitation of timbres, gradual dynamic crescendos, percussive effects.