"Zaïs" was Rameau's first opera which was entirely devoted to "la féerie", the enchanted world of myth from the Middle East with its spirits and fantastic creatures. It was first performed on 29 February 1748 at the Paris Opera and was much praised for its expressive power, elegance and variety of its music as well as for the charm of its ballet.
Although the libretto by Louis de Cahusac was criticised, the delightful work proved very popular: it was revived in 1761 and 1769 and for more than two decades received over 100 performances. Like most of Rameau's operas, "Zaïs" was extensively revised during the composer's lifetime and afterwards. Revisions already began during the first rehearsals and continued until the first performance.
The composer and the librettist Cahusac finally used the Easter period in 1748 to work on those revisions; as well as structural changes and musical substitutions, these included some substantial additions to vocal and instrumental movements. The version which was performed after Easter is more convincing, both musically and dramatically. in contrast, the revivals of 1761 and 1769 – the first after Cahusac's death, the second after Rameau's – contained drastic cuts including the entire prologue.
For the new volume in the "Opera Omnia Rameau" the version from Easter 1748 has been chosen as the primary source. For performances, a choice can be made between this and the original version; a series of insertions links all the passages with another.