He then proceeded to collect the supposed precepts of Zoroaster into a volume, in order to establish a standard of orthodoxy whereto he might require all to conform.

He found the Zoroastrians themselves divided into a number of sects.

Among these he established uniformity by means of a "general council," which was attended by Magi from all parts of the empire, and which settled what was to be regarded as the true Zoroastrian faith.
According to the Oriental writers, this was effected in the following way: Forty thousand, or, according to others, eighty thousand Magi having assembled, they were successively reduced by their own act to four thousand, to four hundred, to forty, and finally to seven, the most highly respected for their piety and learning.

Of these seven there was one, a young but holy priest, whom the universal consent of his brethren recognized as pre-eminent.

His name was Arda-Viraf.