[7] Brochard _Op. cit_. IV. 315.

The fact that has caused the greatest uncertainty in regard to
the date of Sextus is that Claudius Galen in his works mentions
several Sceptics who were also physicians of the Empirical
School,[1] and often speaks of Herodotus, supposed to be
identical with the teacher of Sextus given by Diogenes
Laertius,[2] but makes no reference whatever to Sextus. As
Galen's time passes the limit of the second century A.D., we
must either infer that Sextus was not the well-known physician
that he was stated to be by Pseudo-Galen, and consequently not
known to Galen, or that Galen wrote before Sextus became
prominent as a Sceptic. This silence on the part of Galen in
regard to Sextus increases the doubt, caused by Sextus' own
criticism of the Empirical School of medicine, as to his having
been an Empiricist. The question is made more complicated, as it
is difficult to fix the identity of the Herodotus so often
referred to by Galen.[3] As Galen died about 200 A.D. at the age
of seventy,[4] we should fix the date of Sextus early in the
third century, and that of Diogenes perhaps a little later than
the middle, were it not that early in the third century the
Stoics began to decline in influence, and could hardly have
excited the warmth of animosity displayed by Sextus. We must
then suppose that Sextus wrote at the very latter part of the
second century, and either that Galen did not know him, or that
Galen's books were published before Sextus became prominent
either as a physician or as a Sceptic. The fact that he may have
been better known as the latter than as the former does not
sufficiently account for Galen's silence, as other Sceptics are