Of all the performances at this year's Israel Festival, none will be quite as unique as the Phoenix Ensemble's world premiere of what has become known as the Zapotec Mass, originally written in colonial Mexico almost 400 years ago. "We don't know if it was ever performed [in the 17th century]," explains director Myrna Herzog. "Sometimes there are records of performances, but not in this case." Written by one Andr z Martinez in 1636, the manuscript remained hidden for centuries until being rediscovered in the early 20th century. It made its way into the hands of Dr. Marc Brill, who edited it as part of his masters dissertation and is now a musicologist at the University of Dayton. Following his efforts, it took the Phoenix Ensemble to bring the piece to life. The ensemble performed a partial presentation at the Abu Gosh Music Festival last year, but this year's concert at the Israel Festival is the first full performance of the entire manuscript. The Collegium Tel Aviv joined the ensemble for its performance in Abu Gosh, and will again participate in the performance on Saturday. "It's thrilling," says Hertog, "not only to be the first to do it, but because it is like archaeology; you have to decipher it. It is a privilege because it is very rare for Israelis to do a world premiere [of this kind]." Mexico at the time of the manuscript's creation was a dynamic mix of indigenous Indian, Spanish and African cultures, and the Zapotec Mass reflects this. The opening segments are in Nahuatl, the native Aztec language, and the rest are in traditional Latin. Songs at the end are in old Spanish and an Africanized dialect in use at the time. The whole work is notable for its simple harmonies but extremely complex rhythms, characteristic of masses of that period and place, which were not just a highly formalized form of worship but religious music for the masses that incorporated popular dance and song forms. This period is known among aficionados as the Golden Age of music in the New World, where the combination of cultures produced a distinct style of music. According to Herzog, compositions written in the Americas after 1700 are basically indistinguishable from European music of the same time period. The original manuscript has parts for just four voices, so Herzog expanded it using instruments in use during Baroque Mexico, notably various sizes of bajon (an old-style oboe) as well as percussion. "The Zapotec Mass was written in the 17th century but it has an older flavor, of the 16th. I heard drums in it, and I found a similar mass from the first half of the 16th century where drums were written, so I used it as a model for reconstructing the percussion parts," Herzog expains. The Phoenix Ensemble is the only large group in Israel that performs early music on period instruments, and has a special interest in music from the Americas. The group has produced a CD of 16th century Brazilian music, a disc of Bolivian festival music from 1717, and an innovative recording of the music of great 20th century Brazilian composers Dorival Caymmi and Heitor Villa-Lobos performed on Baroque instruments with modern Brazilian percussion. The ensemble's next CD, already completed and about to be released, is a collection of Renaissance, early Baroque and modern pieces centered around the theme of Jerusalem. Herzog and the Phoenix Ensemble are planning to produce a commercial recording of the Zapotec Mass, and are currently searching for a church in Israel with just the right acoustics for the project. "We may have found one in Jaffa," she says. "We could get the word today and be recording in two weeks." The Phoenix Ensemble and Collegium Tel Aviv perform the Zapotec Mass on Saturday, June 10, at 11 a.m. at the YMCA, 26 King David, Jerusalem. For information and tickets, call 1-700-70-2055 or visit www.israel-festival.org.il.