Luke is the only authority who informs us that
Jesus was thirty years old when he was baptised, and
his statement lies under some suspicion. His text is
much disturbed at this point (iii. 23), and it is not
improbable that it originally ran thus : — " And Jesus
himself, when he began to be God (or divine), was
about thirty years of age, being, as he was legally
reckoned to be, son of Joseph"

Why thirty? Perhaps this number is due to the
belief, vouched for by Jerome and his Hebrew teacher,
of the Jewish rabbis of the first century, that when a
man attains the age of thirty a new soul is born within
him, transcending in moral dignity and value the soul
derived from his mother at birth.
The legend of Zoroaster offers also a striking
parallel to the story of Jesus. Of him it was related
that in his thirtieth year he was enlightened by the
descent upon him of the Vohu mano — i.e., the Good
Thought or Spirit. At the same time he overcame
the evil spirit, Angra Mainyu, or Ahriman, who
offered to him, as Satan offers to Jesus, rule over all
the nations, if he would only renounce the good law
and worship of Mazda, the good deity. The answer
made by the old Persian Redeemer to the Evil One is
similar to that returned by Jesus : " The words taught
by Mazda, these are my weapons, my best weapons. . ..
This I ask thee, Teach me the truth, O Lord." The
Jews had lived much in contact with the Persians, and
had been profoundly influenced by their demonology.
