Body and Soul in Ancient Philosophy

Galen and the Stoics: What each could learn from the other 415
tem radiating from the control-centre and running through the body.
The core functions of the Stoic control-centre, those of coordinating
perception and acting as a source for movement and motivation, are
precisely those of the brain, acting through the nervous system, as
Galen shows by his demonstrations, building on the earlier work of
the Ptolemaic doctors. 22 The logical conclusion is that, as Long points
out, “Chrysippus’ most interesting contributions could fit a brain-centred
model of mind just as well as a cardiovascular one” 23 .
Indeed, in one respect, the brain-centred account works better for
them than for the heart-centred one. A second distinctive feature of
the theory, in most sources at least, is that some functions allocated
by earlier thinkers to psyche, notably growth and nutrition, were ascribed
to what they presented as a lower level of “tension” (material state
and structure), namely nature (physis). Thus, in animals, including
human beings, it would seem, the operation of growth and nutrition
falls under “nature”, while psyche is the agency for the operation of
more advanced functions including perception, movement, and motivation.
24 The brain-centred account could accommodate this distinction
more easily than the heart-centred one. The distinctively psychic functions
could be attributed to the brain and nervous system, whereas the
“natural” functions of growth and nutrition could be allocated to other
organs, such as the heart, stomach or liver. This revised version of the
Stoic theory resolves the problem of understanding how the two levels
of psychic pneuma (“nature” and psyche) operate differently in the same
organ, namely the heart seen as the seat of the unified control-centre. 25
Heinrich von Staden has suggested that the Stoic distinction between
psyche and “nature” (physis), like a comparable one found in
some parts of Galen’s thought, recalls ideas that we find in the work
of the Ptolemaic doctors who pioneered the brain-centred account,
Herophilus and Erasistratus, and that the Stoic use of this distinction
22 See refs. in nn. 10, 14 – 16 above.
23 Long 1999b, 569.
24 Calcidius, exceptionally, presents the control-centre as responsible for nutrition
and growth, as well as locomotion, sensation, and impulse (LS 53 G(6)); but this
is not reflected in other sources. See further Long 1996, 238, Tieleman 1996,
95 – 99, Ju 2007. On the Stoic analysis of the scala naturae in terms of degrees of
“tension” ( tonos), see LS 47, esp. N–Q.
25 This problem is noted by Tieleman 1996, 99.