Flanked by the five musicians of the Dastan Ensemble, on an elevated stage covered with red Moroccan rugs, the Iranian singer Parissa sat, eyes closed. As the late afternoon sun dazzled her green bejeweled caftan and the enormous oak tree that served as a leafy backdrop, Parissa sang love poems in what sounded like equal parts lamentation and controlled euphoria. In the crowded audience that spilled out over the Batha Museum’s courtyard here were Queen Rania of Jordan and U2’s Bono and The Edge, who happened to have been recording there in early June during the festival. Parissa’s voice cyclically climbed and descended multiple notes in one breath with such jarring beauty and intensity that many were moved to tears.

Parissa’s performance was just one of 40-plus that graced the 2007 Fez Festival of World Sacred Music. For 13 years running, the festival has showcased traditional as well as broadly interpreted sacred music. This year featured Pakistani Qawwali, Gregorian chants from Lisbon, the London Community Gospel Choir, Pergolesi’s cantatas sung by Barbara Hendricks and Turkish whirling dervishes. The poetry of Rumi, the Sufi mystic, was pervasive in most of the classical performances, as this year marks the 800th anniversary of his birth.

There was also the afro-pop of Angélique Kidjo, and a handful of outstanding Moroccan rock, hip-hop, funk, pop, fusion groups with messages of peace, tolerance and social justice. The ten day festival also hosted heady morning discussions with topics such as Cultural Identity vs. Globalization, and Faith and Reason in the Modern World. Every night was capped by a free 11 p.m. Sufi performance by a different Moroccan brotherhood in the garden of Dar Tazi, a beautiful old palace.

“We have a target,” said festival founder and president Mohamed Kabbaj, “to get people to know each other.” Sitting on a cushion before the South African Johnny Clegg performed, Mr. Kabbaj noted that ignorance plagues all striations of society. When asked about Morocco and the threat of Islamic extremism, he answered: “The origin of extremism is ignorance. Ignorance creates fear.” Mr. Kabbaj is aware that his festival can’t stop extremism, “but it’s a way, a means, and today we have to use all means.” So far his festival has spawned 27 other scared music festivals world-wide.

All Fez festival venues, some free, others ticketed, were situated around the incredible medieval Medina, a chaotic labyrinth of “streets” and alleys, so narrow they can only be used by donkeys and throngs of pedestrians, most wearing traditional Moroccan clothes.

One of the most visually mesmerizing performances of the festival was by the whirling dervishes, Ayin-i Djém, from Turkey who traditionally only whirl in private. They preformed at Bab Makina, an enormous, majestic, walled-in city gate, transformed into the poshest venue of the festival, with seating under an open sky, a VIP area, and food for sale, attracting the wealthier La Ville Moderne people of Fez. In marked contrast to the Medina, women wore stilettos and plunging necklines, and many a Chanel purse was tossed on the security X-ray machine upon entry. Only a handful of women wore headscarves.

While the foreign festival-going contingent, primarily from North America and Europe, many of whom sported beads, graying hair and newly purchased flowing Moroccan outfits, sat enraptured by the whirling dervishes, some locals in the audience saw it simply as a social event, waved to friends and chatted, both in person and on cell phones.

Another outstanding performance at Bab Makina two nights later was the Tunisian Sonia M’barek, part of a triple bill of female singers of Arab-Andalous songs. M’barek’s sublime voice mixed seamlessly with the strings that repeatedly crescendoed and relented and expressed impassioned yearning for forgiveness, mercy and devotion to the Prophet. She perfectly demonstrated melisma, the singing of multiple notes in one breath. Prevalent in most North African sacred music, melisma can be heard in neighboring Spain’s flamenco.

The city gates of Bab Boujloud held free concerts—repeats of ticketed headliners, as well as many outstanding Moroccan rock groups. Just as Rumi flowed through many of the classical performances, Gnawa, a form of rhythmic Moroccan music brought from sub-Saharan Africa via slaves thousands of years ago, was incorporated into the repertoire of most of the rock groups. Among the instruments heard were the hejhouj, or Gnawan guitar, and qarqabas, handheld Gnawan metal instruments that are clanked together like large castanets and evolved from broken shackles.

One of the best performances at Bab Boujloud was the Gnawa-infused pop of Majda Yahyaoui, who sang with such power and benevolence that the kids in the audience, including girls, tried to climb the metal crowd-control gates to get closer.

“I love our heritage and I want to sing everything Moroccan,” said a smiling Yahyaoui as she donned a white and gold robe backstage after her performance. “I am the first white woman to sing Gnawan music,” she added proudly. Yahyaoui is known for singing Malhoun, another traditionally male genre, and was quick to stress that women used to be forbidden to sing in public (still the law in some Muslim countries). “So there’s been progress!”

The Sufi Nights series surprisingly had the most maniacally delirious, memorable and hypnotizing, performance of the festival, the Ouled Kamar Gnaoua Ensemble. The eight-man ensemble, dressed in brightly colored silken robes embroidered with seashells, took turns singing and dancing across the stage, at first acrobatically, and once with bound feet. They called out to various saints, clapped, sprinkled oils, playing the hejhouj and tinny qarqabas. A steady, reciprocal delirium grew over the course of three hours between the ensemble and the audience, making several teenage girls in the tightly packed garden dramatically flail their hair around, one of whom had to be calmed down by her mother.

Most foreigners had made discreet exits by this point, although a few remained, one of them being the Boston-based composer Osvaldo Golijov, who was “mind-boggled” by what was unfolding. Three men in steady progression fell into trances, each crawling on stage on his hands and knees. One man, seemingly in a state of hypnosis danced around, his eyes little slits, while the other two convulsed and had to eventually be carried off the stage by security.