Printed interventions in eighteenth-century librettos for the performance of Italian opera in London: The roles of commas, inserts, and pasteovers

Among the routines (or rituals) for a Londoner going to the Opera House in the eighteenth-century was the purchase of the book of the words of the opera about to be attended. Such a routine was also in place for those attending performances at the London playhouses, but there was one feature of the libretto for the Opera which made its acquisition both important and fundamentally different: the libretto contained a parallel English translation of the text, for all the works performed there were sung in Italian, and it was, in effect, an eighteenth-century system of surtitles. Imagine, therefore, the annoyance of a patron, who, having followed the opera for half an act, began to find that what was happening on the stage in front of him was becoming less and less like the text that appeared in the expensively acquired book. But surely, it might be asked, an opera is an opera, and doesn't a published libretto simply represent what was performed? Hints that this might not be the case can be found from the very first years after the arrival of Italian opera in London.