These filters affect the way composers and librettists approach a source - and serve to realise that text, distort it or transfigure it.
During the late 1820s and early 1830s librettists increasingly eliminated traditional distinctions of dramatic function.
This was a matter of grave importance, and not only for the playwrights and librettists.
What these avvertimenti by the librettists offer is a glimpse into the backstage intrigues that accompanied the staging of these innovative works.
None the less, the composer's imploring letters to his errant librettist provide an interesting insight into his world of ideas at the time.
Composers took longer to complete a work; librettists were reduced in status; the visual took primacy over all else.
Payments for his services also lagged far behind stipends paid to the principals, librettists, choreographers and scenographers.
But it has a great deal more, including entries on living and deceased composers, librettists, singers, conductors and writers about opera.
