The purpose of this short essay is to announce a new research project, ‘The Aria in the Italian Libretto in London before 1800’, the aim of which is to list the incipits of all the arias included in Italian-language opera and oratorio librettos printed in London before the turn of the nineteenth century. The notion that an opera libretto may not be the stable text it appears on the page to be is no news to scholars working on opera and musical theatre, who understand perfectly well the possible nature and origins of the sources they use, especially the libretto. At least one hopes they do; but in the case of the last, do they? The seductive lure of the printed page is strong, a lure which has an almost irresistible pull for scholars when there is a score to ‘match’; it becomes even stronger when those working on canonic composers stray out of their chosen territory to look for ‘contemporaneous examples’ from the works of ‘minor composers’, or when there is no thematic catalogue to provide even a basic chart with which to navigate the treacherous waters of the output of even some major eighteenth-century ones. A libretto is, after all, not ‘music’, they say – ‘that’s all very well, but why aren’t you talking about the music?’ – so why worry? Just hurry on to the matching score to identify the ‘composer’s intentions’, and all will be well.