and is not mentioned elsewhere in Aristotle’s or Theophrastos’ treatises. On the other
hand similarities exist between some of Diokle ̄s’ ideas and some of those developed by
Aristotle and his circle as well as by some Hippokratic writings of M and
P.
Writings. Diokle ̄s’ writings are encyclopedic in range: at least 20 titles (some in four or
more books) on subjects as varied as prognostics (On prognosis), physiology (On digestion),
diagnostics and therapy (Affection, Cause, Treatment and On treatments), gynecology (Matters
related to women), bandages (On bandages), surgery (On things in the surgery), regimen in health
(Matters of Health to Pleistarkhos, his most influential work), food and wines, herbs (On Rootcut-
ting), olive oil for massage (Arkhidamos), drugs, poisons (On lethal drugs), etc. Among many
strictly technical treatises devoted to particular fields of medicine (e.g., surgical instruments
or bandages), some of his works (Matters of Health to Pleistarkhos and Arkhidamos) apparently
addressed a larger non-specialist audience. His books, in Attic dialect, long remained avail-
able: G read first-hand Arkhidamos and Affections, Cause, Treatment, plus Matters of Health,
of which he knew variant editions in circulation (fr.188); On things in the surgery circulated
in Gale ̄n’s time under various titles (fr.160a). Even O probably compiled his
medical encyclopedia copying directly from Diokle ̄s’ works.
Doctrine. Diokle ̄s generally agrees with Hippokrate ̄s on most important issues (he uses
notions such as krisis, “resolution,” “concoction,” humors), and his doctrines are fre-
quently conflated with those of other ancient authorities, making it difficult to reconstruct
Diokle ̄s’ own ideas. Precisely aware of methodological questions, Diokle ̄s tends to relate his
medical views to more general views on nature. Like Hippokrate ̄s, he believes that treatment
of a body-part cannot be effective without considering the body as a whole (fr.61) or the
essence of the disease, and he privileges external climatic factors as causes of disease
(frr.54–55). He uses inference from signs and refers to hidden causes (frr.56, 177), and was
accordingly classified among the Dogmatists (frr.13–16). However, believing in an alliance
between reason and experience, Diokle ̄s is always concerned with empirical confirmation
both for pathological inner processes (frr.60, 137, 176) and anatomy (repeated dissections in
fr.24). Diokle ̄s is interested in comparative animal anatomy and physiology (frr.24, 39) and
in teleological explanations of bodily structures and processes (fr.23). S preferen-
tially quotes Diokle ̄s’ detailed description (frr.22–23) of the anatomy of the female repro-
ductive organs, including breast-like offshoots inside the uterus (the kotuledons of, e.g., the
H C, A 5.45). He argues against the Aristotelian view that
semen is concocted blood (fr.40), claiming instead that semen is pneuma, which, unlike
blood, has the power of self-movement and is generated directly out of nutrition: semen has
its origin ultimately in the brain (frr.40, 41a). The psychic pneuma, a kind of breath
different from the air inhaled by respiration for the purpose of cooling the innate heat
(fr.31), seems to originate, however, in the heart and is responsible for distributing con-
sciousness and voluntary movement over the body (frr.78, 80, 98). The he ̄gemonikon is
primarily located in the heart, whence the pneuma moves upwards to the head and the
brain: the blood probably carries the pneuma through the vascular system. The
A B (fr.40) attributes to him the four-humor doctrine, each pro-
duced by nutriment, although their physiological and/or pathological role does not
emerge clearly from the other fragments. Obstructions to the pneuma in passages or
vessels through which it is distributed are caused by phlegm (frr.95, 98, occasionally by bile,
fr.108) and cause affections such as lethargy, paralysis, epilepsy (sharing Praxagoras’ view).
In fact what causes fever is “blockage at the end of the veins” (fr.63) and blockages feature
DIOKLE ̄S OF KARUSTOS