Music scholars have turned repeatedly to musical artefacts (manuscript sources and printed libretti) to resolve conflicts, but these merely reflect the underlying confusion that inheres in primary sources. Intelligence reports, compiled weekly for various political and ecclesiastical bodies, provide a more secure basis for dating but any single series survives only sporadically.
Through a coordinated reading of twelve series of such documents against the six bibliographies and the two types of artefacts it has been possible to date, usually to the day, roughly 90% of the 800 operas produced in Venice between 1675 and 1750. This accumulated list resolves almost all problems of year-dating and fully defines the ever-changing limits of the seasons, not only for opera but also for comedy and certain kinds of private entertainments.
This accumulation of chronologically ordered information, besides including
many first-person descriptions of performances, defines important correlates
of patronage, literary subject, and musical genre. Changes over broad
stretches of time are also apparent. Among these the persistence
of elements of courtly organization in the later seventeenth century and
the changing relationship of opera and comedy in the early eighteenth century
are particularly noteworthy.