0 the words that are sung or spoken in a musical work for the theatre
1 the words that are sung or spoken in an opera or similar musical performance
In opera, the presence of a libretto seems to provide both motivation for these questions and ready answers.
I have compared the eighteenth-century libretti, which give a fair approximation of the changes made in 1754.
Apart from these three moments and other slight alterations in the recitative, the 1812 libretto closely resembles the 1806 version.
None of the other librettos consulted for this study contains a trace of the alteration, nor do any reviews mention that such a change occurred.
Accompanying such analyses we find stories within stories, plot summaries that present an (often complicated) opera in miniature, making the libretto manageable.
Eighty-nine little books, or libretti, produced for these semi-staged concerts over a 150-year period, have survived.
While he concedes 'undoubted musical qualities', he finds that the libretto renders the opera obsolete, no longer acceptable.
Some musicologists have argued for a relationship between the thirty-four chords and later musical statements in the opera, statements tied to both plot and libretto.