Zoroastrians say the sacred spring at Chak Chak, a shrine perched beneath a towering cliff face in the searing desert of central Iran, has lost none of its miraculous healing powers.
"A 32-year-old Muslim came here as a last resort when he was dying from leukemia. I was not sure we should let a Muslim in but he insisted and spent the night here," said Goshtasb Belivani, a priest of Iran's ancient pre-Islamic religion.
"During the night he was visited by a beautiful woman dressed in green who gave him sherbet to drink," he continued.
For the last three months, since being given the all clear from his doctor, the young man has been a regular visitor to the shrine.
The beautiful woman was the ghost of Nikbanou, a 7th century Persian princess who fled to the mountain refuge, escaping Arab horsemen who thundered across the border and planted the green pennants of Islam in Iranian soil.
Islam spread quickly in a society where the priestly and royal elite had alienated most classes beneath them.
Now there are only 30,000 followers of the ancient religion among the Islamic Republic's 66 million people, down from 60,000 at the time of the 1979 Islamic revolution.
Zoroastrians see life as an eternal conflict between their good God Ahura Mazda and Ahriman, the embodiment of evil.
Followers of the prophet Zoroaster, who died in the 6th century B.C., say the central tenets of their faith are: "Good thoughts, good words, good deeds."
In early summer, Zoroastrians from across the world meet at the shrine where Nikbanou sought refuge. During the scorching daylight hours they doze on rugs, have picnics and attend prayers in the cool grotto shrine around the flame focal to their worship.
Toward evening, the atmosphere gets far more convivial. Young Zoroastrian men in cowboy hats jive away as one of their friends plays catchy tunes on his Yamaha keyboard.
Girls with free-flowing hair, wearing bright dresses, play catch and giggle while prayers in Avestan, the ancient religious language of the Zoroastrians, are read out over a loud-speaker system.
The Islamic Republic's strict rules on dress and wine are relaxed in the private spaces of the religious minorities.
STAY OR EMIGRATE?
Iran's Shi'ite Muslims are generally tolerant of the ancient religion.
"We get on fine, we use each other's shops and chat every day," said Mohammad Ali Karimi, who teaches Islamic history and religion in a primary school in the nearby city of Yazd, 250 miles southeast of Tehran.
"But many of them are emigrating or becoming Muslims," he added.
The Towers of Silence, the two outcrops where Yazd's Zoroastrians used to leave their dead for the vultures, are now a picnic spot.
Many Zoroastrians at Chak Chak said whole families would convert to Islam if someone married outside the community so they would not be denied inheritance payments under Iranian law.
Zoroastrians have their own member of parliament and hold high positions in bodies such as the Oil Ministry. They say their communities are more vibrant in Canada and Australia.
In India, where they are known as Parsis, the community is more than 60,000 strong.
"Many reckon they will do better as doctors and engineers abroad. If I had a second chance, I would probably emigrate," said priest Esfandiar Dastour, 73.
Former parliamentarian Khosro Dabestani insisted problems for Zoroastrians were the same as those for most Iranians but many disagreed.
Some said friends and family had been denied jobs teaching in universities because they were Zoroastrians. Another mentioned being booted out of a chess team just before reaching national level.
"One Muslim elder confiscated our land in a village I know saying 'This is an Islamic country, the land belongs to us'," said one woman.
Another woman, Golchehreh, protested about dress codes.
"I am not a Muslim, why should I have to wear these headscarves?," she complained.
But gray-bearded Zoroastrian pilgrim Iraj thought they had all missed the point.
"There are no mosques, churches and synagogues. They are all in your own heart," he said.
"This shrine is a sham. You need to be out there alone with your God under the sun in the wilderness," he said, pointing into the shimmering whiteness of the desert.