festival was already well established in the Achæmenian
period.

All the Magi were not necessarily devoted to the priesthood; but
those only became apt in the execution of their functions who had been
dedicated to them from infancy, and who, having received the necessary
instruction, were duly consecrated. These adepts were divided into
several classes, of which three at least were never confounded in their
functions--the sorcerers, the interpreters of dreams, and the most
venerated sages--and from these three classes were chosen the ruling
body of the order and its supreme head. Their rule of life was
strict and austere, and was encumbered with a thousand observances
indispensable to the preservation of perfect purity in their persons,
their altars, their victims, and their sacrificial vessels and
implements. The Magi of highest rank abstained from every form of
living thing as food, and the rest only partook of meat under certain
restrictions. Their dress was unpretentious, they wore no jewels, and
observed strict fidelity to the marriage vow;* and the virtues with
which they were accredited obtained for them, from very early times,
unbounded influence over the minds of the common people as well as over
those of the nobles: the king himself boasted of being their pupil, and
took no serious step in state affairs without consulting Ahura-mazdâ or
the other gods by their mediation. The classical writers maintain that
the Magi often cloaked monstrous vices under their apparent strictness,
and it is possible that this was the case in later days, but even then
moral depravity was probably rather the exception than the rule among
them:*** the majority of the Magi faithfully observed the rules of
honest living and ceremonial purity enjoined on them in the books handed
down by their ancestors.