because there are
many things which prevent one from knowing that, namely, both the
uncertainty of the matter and the shortness of man's life." On this
account, it is said, he was charged with impiety at Athens and was
outlawed, and his works were publicly burned. The date of this trial is
not known for certain; but it is reasonably supposed to have coincided
with that of Diagoras, namely, in 415. At any rate it must have taken
place after 423-421, as we know that Protagoras was at that time staying
in Athens. As he must have been born about 485, the charge overtook him
when old and famous; according to one account, his work on the gods seems
to belong to his earlier writings.

To doubt the correctness of this tradition would require stronger reasons
than we possess, although it is rather strange that the condemnation of
Protagoras is mentioned neither in our historical sources nor in
Aristophanes, and that Plato, who mentions Protagoras rather frequently as
dead, never alludes to it. At any rate, the quotation from the work on the
gods is certainly authentic, for Plato himself referred to it. Hence it is
certain that Protagoras directly stated the problem as to the existence of
the gods and regarded it as an open question. But beyond that nothing much
can be deduced from the short quotation; and as to the rest of the book on
the gods we know nothing. The meagre reasons for scepticism adduced
probably do not imply any more than that the difficulties are objective as
well as subjective. If, in the latter respect, the brevity of life is
specially mentioned it may be supposed that Protagoras had in mind a
definite proof of the existence of the gods which was rendered difficult
by the fact that life is so brief; prediction of the future may be guessed
at, but nothing certain can be stated.

Protagoras is the only one of the sophists of whom tradition says that he
was the object of persecution owing to his religious views. The trial of
Socrates, however, really belongs to the same category when looked at from
the accusers' point of view; Socrates was accused as a sophist. But as his
own attitude towards popular religion differed essentially from that of
the sophists, we cannot consider him in this connexion. Protagoras's trial
itself is partly determined by special circumstances. In all probability
it took place at a moment when a violent religious reaction had set in at
Athens owing to some grave offences against the public