Plato's Timaeus

TIMAEUS

by Plato

Translated by Benjamin Jowett

Section 6.

I shall not attempt to connect the physiological speculations of Plato
either with ancient or modern medicine. What light I can throw upon them
will be derived from the comparison of them with his general system.

There is no principle so apparent in the physics of the Timaeus, or in
ancient physics generally, as that of continuity. The world is conceived
of as a whole, and the elements are formed into and out of one another; the
varieties of substances and processes are hardly known or noticed. And in
a similar manner the human body is conceived of as a whole, and the
different substances of which, to a superficial observer, it appears to be
composed--the blood, flesh, sinews--like the elements out of which they are
formed, are supposed to pass into one another in regular order, while the
infinite complexity of the human frame remains unobserved. And diseases
arise from the opposite process--when the natural proportions of the four
elements are disturbed, and the secondary substances which are formed out
of them, namely, blood, flesh, sinews, are generated in an inverse order.

Plato found heat and air within the human frame, and the blood circulating
in every part. He assumes in language almost unintelligible to us that a
network of fire and air envelopes the greater part of the body. This outer
net contains two lesser nets, one corresponding to the stomach, the other
to the lungs; and the entrance to the latter is forked or divided into two
passages which lead to the nostrils and to the mouth. In the process of
respiration the external net is said to find a way in and out of the pores
of the skin: while the interior of it and the lesser nets move alternately
into each other. The whole description is figurative, as Plato himself
implies when he speaks of a 'fountain of fire which we compare to the
network of a creel.' He really means by this what we should describe as a
state of heat or temperature in the interior of the body. The 'fountain of
fire' or heat is also in a figure the circulation of the blood. The
passage is partly imagination, partly fact.

He has a singular theory of respiration for which he accounts solely by the
movement of the air in and out of the body; he does not attribute any part
of the process to the action of the body itself. The air has a double
ingress and a double exit, through the mouth or nostrils, and through the
skin. When exhaled through the mouth or nostrils, it leaves a vacuum which
is filled up by other air finding a way in through the pores, this air
being thrust out of its place by the exhalation from the mouth and
nostrils. There is also a corresponding process of inhalation through the
mouth or nostrils, and of exhalation through the pores. The inhalation
through the pores appears to take place nearly at the same time as the
exhalation through the mouth; and conversely. The internal fire is in
either case the propelling cause outwards--the inhaled air, when heated by
it, having a natural tendency to move out of the body to the place of fire;
while the impossibility of a vacuum is the propelling cause inwards.

Thus we see that this singular theory is dependent on two principles
largely employed by Plato in explaining the operations of nature, the
impossibility of a vacuum and the attraction of like to like. To these
there has to be added a third principle, which is the condition of the
action of the other two,--the interpenetration of particles in proportion
to their density or rarity. It is this which enables fire and air to
permeate the flesh.

Plato's account of digestion and the circulation of the blood is closely
connected with his theory of respiration. Digestion is supposed to be
effected by the action of the internal fire, which in the process of
respiration moves into the stomach and minces the food. As the fire
returns to its place, it takes with it the minced food or blood; and in
this way the veins are replenished. Plato does not enquire how the blood
is separated from the faeces.

Of the anatomy and functions of the body he knew very little,--e.g. of the
uses of the nerves in conveying motion and sensation, which he supposed to
be communicated by the bones and veins; he was also ignorant of the
distinction between veins and arteries;--the latter term he applies to the
vessels which conduct air from the mouth to the lungs;--he supposes the
lung to be hollow and bloodless; the spinal marrow he conceives to be the
seed of generation; he confuses the parts of the body with the states of
the body--the network of fire and air is spoken of as a bodily organ; he
has absolutely no idea of the phenomena of respiration, which he attributes
to a law of equalization in nature, the air which is breathed out
displacing other air which finds a way in; he is wholly unacquainted with
the process of digestion. Except the general divisions into the spleen,
the liver, the belly, and the lungs, and the obvious distinctions of flesh,
bones, and the limbs of the body, we find nothing that reminds us of
anatomical facts. But we find much which is derived from his theory of the
universe, and transferred to man, as there is much also in his theory of
the universe which is suggested by man. The microcosm of the human body is
the lesser image of the macrocosm. The courses of the same and the other
affect both; they are made of the same elements and therefore in the same
proportions. Both are intelligent natures endued with the power of self-
motion, and the same equipoise is maintained in both. The animal is a sort
of 'world' to the particles of the blood which circulate in it. All the
four elements entered into the original composition of the human frame; the
bone was formed out of smooth earth; liquids of various kinds pass to and
fro; the network of fire and air irrigates the veins. Infancy and
childhood is the chaos or first turbid flux of sense prior to the
establishment of order; the intervals of time which may be observed in some
intermittent fevers correspond to the density of the elements. The spinal
marrow, including the brain, is formed out of the finest sorts of
triangles, and is the connecting link between body and mind. Health is
only to be preserved by imitating the motions of the world in space, which
is the mother and nurse of generation. The work of digestion is carried on
by the superior sharpness of the triangles forming the substances of the
human body to those which are introduced into it in the shape of food. The
freshest and acutest forms of triangles are those that are found in
children, but they become more obtuse with advancing years; and when they
finally wear out and fall to pieces, old age and death supervene.

As in the Republic, Plato is still the enemy of the purgative treatment of
physicians, which, except in extreme cases, no man of sense will ever
adopt. For, as he adds, with an insight into the truth, 'every disease is
akin to the nature of the living being and is only irritated by
stimulants.' He is of opinion that nature should be left to herself, and
is inclined to think that physicians are in vain (Laws--where he says that
warm baths would be more beneficial to the limbs of the aged rustic than
the prescriptions of a not over-wise doctor). If he seems to be extreme in
his condemnation of medicine and to rely too much on diet and exercise, he
might appeal to nearly all the best physicians of our own age in support of
his opinions, who often speak to their patients of the worthlessness of
drugs. For we ourselves are sceptical about medicine, and very unwilling
to submit to the purgative treatment of physicians. May we not claim for
Plato an anticipation of modern ideas as about some questions of astronomy
and physics, so also about medicine? As in the Charmides he tells us that
the body cannot be cured without the soul, so in the Timaeus he strongly
asserts the sympathy of soul and body; any defect of either is the occasion
of the greatest discord and disproportion in the other. Here too may be a
presentiment that in the medicine of the future the interdependence of mind
and body will be more fully recognized, and that the influence of the one
over the other may be exerted in a manner which is not now thought
possible.