Timaeus
movement may be supposed to be as follows. In the interior of
every animal the hottest part is that which is around the blood
and veins; it is in a manner an internal fountain of fire, which
we compare to the network of a creel, being woven all of fire and
extended through the centre of the body, while the outer parts
are composed of air. Now we must admit that heat naturally
proceeds outward to its own place and to its kindred element; and
as there are two exits for the heat, the one out through the
body, and the other through the mouth and nostrils, when it moves
towards the one, it drives round the air at the other, and that
which is driven round falls into the fire and becomes warm, and
that which goes forth is cooled. But when the heat changes its
place, and the particles at the other exit grow warmer, the
hotter air inclining in that direction and carried towards its
native element, fire, pushes round the air at the other; and this
being affected in the same way and communicating the same
impulse, a circular motion swaying to and fro is produced by the
double process, which we call inspiration and expiration.
The phenomena of medical cupping-glasses and of the swallowing of
drink and of the projection of bodies, whether discharged in the
air or bowled along the ground, are to be investigated on a
similar principle; and swift and slow sounds, which appear to be
high and low, and are sometimes discordant on account of their
inequality, and then again harmonical on account of the equality
of the motion which they excite in us. For when the motions of
the antecedent swifter sounds begin to pause and the two are
equalized, the slower sounds overtake the swifter and then propel
them. When they overtake them they do not intrude a new and
discordant motion, but introduce the beginnings of a slower,
which answers to the swifter as it dies away, thus producing a
single mixed expression out of high and low, whence arises a
pleasure which even the unwise feel, and which to the wise
becomes a higher sort of delight, being an imitation of divine
harmony in mortal motions. Moreover, as to the flowing of water,
the fall of the thunderbolt, and the marvels that are observed
about the attraction of amber and the Heraclean stones,—in none
of these cases is there any attraction; but he who investigates
rightly, will find that such wonderful phenomena are attributable
to the combination of certain conditions—the non-existence of a
vacuum, the fact that objects push one another round, and that
they change places, passing severally into their proper positions
as they are divided or combined.
Such as we have seen, is the nature and such are the causes of
respiration,—the subject in which this discussion originated. For
the fire cuts the food and following the breath surges up within,
fire and breath rising together and filling the veins by drawing
up out of the belly and pouring into them the cut portions of the
food; and so the streams of food are kept flowing through the
whole body in all animals. And fresh cuttings from kindred
substances, whether the fruits of the earth or herb of the field,
which God planted to be our daily food, acquire all sorts of
colours by their inter-mixture; but red is the most pervading of
them, being created by the cutting action of fire and by the
impression which it makes on a moist substance; and hence the
liquid which circulates in the body has a colour such as we have
described. The liquid itself we call blood, which nourishes the
flesh and the whole body, whence all parts are watered and empty
places filled.
Now the process of repletion and evacuation is effected after the
manner of the universal motion by which all kindred substances
are drawn towards one another. For the external elements which
surround us are always causing us to consume away, and
distributing and sending off like to like; the particles of
blood, too, which are divided and contained within the frame of
the animal as in a sort of heaven, are compelled to imitate the
motion of the universe. Each, therefore, of the divided parts
within us, being carried to its kindred nature, replenishes the
void. When more is taken away than flows in, then we decay, and
when less, we grow and increase.
The frame of the entire creature when young has the triangles of
each kind new, and may be compared to the keel of a vessel which
is just off the stocks; they are locked firmly together and yet
the whole mass is soft and delicate, being freshly formed of
marrow and nurtured on milk. Now when the triangles out of which
meats and drinks are composed come in from without, and are
comprehended in the body, being older and weaker than the
triangles already there, the frame of the body gets the better of
them and its newer triangles cut them up, and so the animal grows
great, being nourished by a multitude of similar particles. But
when the roots of the triangles are loosened by having undergone
many conflicts with many things in the course of time, they are
no longer able to cut or assimilate the food which enters, but
are themselves easily divided by the bodies which come in from
without. In this way every animal is overcome and decays, and
this affection is called old age. And at last, when the bonds by
which the triangles of the marrow are united no longer hold, and
are parted by the strain of existence, they in turn loosen the
bonds of the soul, and she, obtaining a natural release, flies
away with joy. For that which takes place according to nature is
pleasant, but that which is contrary to nature is painful. And
thus death, if caused by disease or produced by wounds, is
painful and violent; but that sort of death which comes with old
age and fulfils the debt of nature is the easiest of deaths, and
is accompanied with pleasure rather than with pain.
Now every one can see whence diseases arise. There are four
natures out of which the body is compacted, earth and fire and
water and air, and the unnatural excess or defect of these, or
the change of any of them from its own natural place into
another, or—since there are more kinds than one of fire and of
the other elements—the assumption by any of these of a wrong
kind, or any similar irregularity, produces disorders and
diseases; for when any of them is produced or changed in a manner
contrary to nature, the parts which were previously cool grow
warm, and those which were dry become moist, and the light become
heavy, and the heavy light; all sorts of changes occur. For, as
we affirm, a thing can only remain the same with itself, whole
and sound, when the same is added to it, or subtracted from it,
in the same respect and in the same manner and in due proportion;
and whatever comes or goes away in violation of these laws causes
all manner of changes and infinite diseases and corruptions. Now
there is a second class of structures which are also natural, and
this affords a second opportunity of observing diseases to him
who would understand them. For whereas marrow and bone and flesh
and sinews are composed of the four elements, and the blood,
though after another manner, is likewise formed out of them, most
diseases originate in the way which I have described; but the
worst of all owe their severity to the fact that the generation
of these substances proceeds in a wrong order; they are then
destroyed. For the natural order is that the flesh and sinews
should be made of blood, the sinews out of the fibres to which
they are akin, and the flesh out of the clots which are formed
when the fibres are separated. And the glutinous and rich matter
which comes away from the sinews and the flesh, not only glues
the flesh to the bones, but nourishes and imparts growth to the
bone which surrounds the marrow; and by reason of the solidity of
the bones, that which filters through consists of the purest and
smoothest and oiliest sort of triangles, dropping like dew from
the bones and watering the marrow. Now when each process takes
place in this order, health commonly results; when in the
opposite order, disease. For when the flesh becomes decomposed
and sends back the wasting substance into the veins, then an
over-supply of blood of diverse kinds, mingling with air in the
veins, having variegated colours and bitter properties, as well
as acid and saline qualities, contains all sorts of bile and
serum and phlegm. For all things go the wrong way, and having
become corrupted, first they taint the blood itself, and then
ceasing to give nourishment to the body they are carried along
the veins in all directions, no longer preserving the order of
their natural courses, but at war with themselves, because they
receive no good from one another, and are hostile to the abiding
constitution of the body, which they corrupt and dissolve. The
oldest part of the flesh which is corrupted, being hard to
decompose, from long burning grows black, and from being
everywhere corroded becomes bitter, and is injurious to every
part of the body which is still uncorrupted. Sometimes, when the
bitter element is refined away, the black part assumes an acidity
which takes the place of the bitterness; at other times the
bitterness being tinged with blood has a redder colour; and this,
when mixed with black, takes the hue of grass; and again, an
auburn colour mingles with the bitter matter when new flesh is
decomposed by the fire which surrounds the internal flame;—to all
which symptoms some physician perhaps, or rather some
philosopher, who had the power of seeing in many dissimilar
things one nature deserving of a name, has assigned the common
name of bile. But the other kinds of bile are variously
distinguished by their colours. As for serum, that sort which is
the watery part of blood is innocent, but that which is a
secretion of black and acid bile is malignant when mingled by the
power of heat with any salt substance, and is then called acid
phlegm. Again, the substance which is formed by the liquefaction
of new and tender flesh when air is present, if inflated and
encased in liquid so as to form bubbles, which separately are
invisible owing to their small size, but when collected are of a
bulk which is visible, and have a white colour arising out of the
generation of foam—all this decomposition of tender flesh when
intermingled with air is termed by us white phlegm. And the whey
or sediment of newly-formed phlegm is sweat and tears, and
includes the various daily discharges by which the body is
purified. Now all these become causes of disease when the blood
is not replenished in a natural manner by food and drink but
gains bulk from opposite sources in violation of the laws of
nature. When the several parts of the flesh are separated by