Body and Soul in Ancient Philosophy

416
Christopher Gill
may reflect their influence, on Chrysippus at least. 26 The relevant distinctions
are, in the case of Herophilus, between (1) the operation of
sensation, movement, and voluntary action (prohairesis) through the
nerves, and (2) involuntary movements, such as pulse and respiration,
which Herophilus calls “natural activities”. Erasistratus sees the body
as interpenetrated by “triple webs” (triplokiai) of arteries, veins and
nerves. (1) Psychic pneuma, conveyed from the brain through the
nerves, acts as the vehicle of sensation, cognition, and movement,
while (2) “natural activities”, such as pulse, respiration, digestion and reproduction,
are administered by blood or “natural” pneuma. 27 There are,
in fact, some indications that Chrysippus responded to their views (or, at
least, to arguments for the brain-centred view), though he resisted those
arguments. 28 However, whether or not we accept the idea that the Ptolemaic
doctors actually influenced Stoic thought in this respect, this
point of resemblance suggests that the Stoics could have adopted the
brain-centred anatomical picture. Thus, in certain ways, this picture
would have suited the distinctive features of their psychological theory
better than the heart-centred picture they adopted, in addition to the
methodological advantages discussed earlier.
Galen’s anatomy and Stoic psychology
In Galen’s case, I want to mount an analogous argument. I think his
theory would have been much more coherent and tenable if he had advanced
a view more like that of the Stoics, one which adopted the idea
of a unified psychological centre while attributing sub-psychological
processes to “nature”. As just suggested in the case of the Stoics, this
kind of view is entirely compatible with the brain-centred account advanced
by the Ptolemaic doctors and by Galen. The great merit of
adopting a more Stoic-style psychology would have been that Galen
would have avoided a series of problems and inconsistencies that arise
in the account that he actually offers in PHP Books 1–3 (and 6), as
has been pointed out in some recent discussions. Virtually all these prob-
26 The dates (all BC) of these thinkers are: Herophilus (ca. 330 – 250), Erasistratus
(ca. 320 –240), and Chrysippus (ca. 280 – ca. 206).
27 See von Staden 2000, 88 –90, 95 –96, 101–104.
28 See Gal. PHP V.255, 2.5.70, and V.189, 1.7.1; also Tieleman 1996, 51 – 52,
83 – 86.