Diocles of Carystus on the method of dietetics 97
Hippocratic writings asOn FleshesorOn Regimenfor that matter.^50 Nor
are the words ‘a certain Diocles’ (Diocli cuidam) in Pliny’s paraphrase of
this Theophrastean testimony (fr. 239 b) to be interpreted as evidence that
Theophrastus referred to another Diocles:^51 they indicate that Pliny was
(just as we are, and perhaps for similar reasons) in doubt whether the Diocles
mentioned by his source Theophrastus was identical with the Diocles of
Carystus known to him from other sources.^52 If Pliny knew for certain
that another Diocles was meant – and how could he do so otherwise than
because of autopsy of the text of this other Diocles or because he knew from
other sources that Theophrastus referred to a text by another Diocles – he
would never have expressed himself in this way. Of course we cannot prove
that the Diocles mentioned by Theophrastus is the Carystian physician;
but then there are a great number of other testimonies about a Diocles
where this proof cannot be given.
What we can say, I think, is that Diocles marks a methodological aware-
ness of the limits of causal explanation that was not anticipated in the
Hippocratic Corpus and that showed several significant resemblances to
remarks found in Aristotle and Theophrastus. These resemblances may
have been the result of intellectual exchange and discussion between them
(the existence of which is likely), but this cannot be proved, and we are in
no position to decide who was ‘influenced’ by whom.
Finally, it seems that any association of Diocles with Empiricism or
Scepticism should be abandoned once and for all. Those who have read
the fragment in this way not only seem to have extrapolated Diocles’ re-
marks about dietetics to all other branches of medicine (on the question
whether this is justified, see above), but also, as far as dietetics itself is con-
cerned, to have been guided by Galen’s presentation of it, that is, as propa-
ganda for an exclusively empirical approach to the search for the powers of
(^50) It has been argued by von Staden ( 1992 , 253 ) that there is no independent evidence of mineralogist
interest by Diocles. But in fr. 22 Diocles displays a detailed interest in the cohesion between various
sorts of objects, including wood and stones. The fragment is quoted by Galen in the context
of embryology, but there is no evidence that in its original context it just served the purpose of
analogy (as it does for Galen). Moreover, as von Staden concedes, in the immediate context of the
Diocles fragment inOn Stones, Theophrastus mentions dietetic and physiological factors affecting
the magnetic force of thelyngourion– although I agree that this does notprovethat the Diocles
mentioned was Diocles of Carystus.
(^51) Pliny,Natural History 27. 53 : ‘what Theophrastus attributed to a certain Diocles’ (quod Diocli cuidam
Theophrastus quoque credidit).
(^52) Contra Kudlien ( 1963 , 462 – 3 ), who infers from this that the Theophrastus testimony ‘mit aller
Wahrscheinlichkeit’ and ‘offenbar’ refers to another Diocles; and von Staden ( 1992 , 253 ), who says
that Pliny’s wording implies ‘that the two [i.e. the Diocles mentioned by Theophrastus and the
Diocles of Carystus known to Pliny from other sources] are not identical’.