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11
We must investigate in the light of the results we have arrived at
what solid or liquid bodies are hot and what cold.
Bodies consisting of water are commonly cold, unless (like
lye,
urine, wine) they contain foreign heat. Bodies consisting of
earth, on
the other hand, are commonly hot because heat was active in forming
them: for instance lime and ashes.
We must recognize that cold is in a sense the matter of bodies.
For the dry and the moist are matter (being passive) and earth and
water are the elements that primarily embody them, and they are
characterized by cold. Consequently cold must predominate in every
body that consists of one or other of the elements simply, unless such
a body contains foreign heat as water does when it boils or when it
has been strained through ashes. This latter, too, has acquired heat
from the ashes, for everything that has been burnt contains more or
less heat. This explains the generation of animals in putrefying
bodies: the putrefying body contains the heat which destroyed its
proper heat.
Bodies made up of earth and water are hot, for most of them derive
their existence from concoction and heat, though some, like the
waste products of the body, are products of putrefaction. Thus
blood, semen, marrow, figjuice, and all things of the kinds are hot as
long as they are in their natural state, but when they perish and fall
away from that state they are so no longer. For what is left of them
is their matter and that is earth and water. Hence both views are held
about them, some people maintaining them to be cold and others to be
warm; for they are observed to be hot when they are in their natural
state, but to solidify when they have fallen away from it. That, then,
is the case of mixed bodies. However, the distinction we laid down
holds good: if its matter is predominantly water a body is cold (water
being the complete opposite of
fire), but if earth or
air it tends
to be warm.
It sometimes happens that the coldest bodies can be raised to the
highest temperature by foreign heat; for the most solid and the
hardest bodies are coldest when deprived of heat and most burning
after exposure to fire: thus water is more burning than
smoke and
stone than water.
12
Having explained all this we must describe the
nature of flesh,
bone, and the other homogeneous bodies severally.
Our account of the formation of the homogeneous bodies has given
us the elements out of which they are compounded and the classes
into which they fall, and has made it clear to which class each of
those bodies belongs. The homogeneous bodies are made up of the
elements, and all the works of nature in turn of the homogeneous
bodies as matter. All the homogeneous bodies consist of the elements
described, as matter, but their essential nature is determined by
their definition. This fact is always clearer in the case of the later
products of those, in fact, that are instruments, as it were, and have
an end: it is clearer, for instance, that a dead man is a man only
in name. And so the hand of a dead man, too, will in the same way be a
hand in name only, just as stone flutes might still be called
flutes: for these members, too, are instruments of a kind. But in
the case of flesh and bone the fact is not so clear to see, and in
that of fire and water even less. For the end is least obvious there
where matter predominates most. If you take the extremes, matter is
pure matter and the essence is pure definition; but the bodies
intermediate between the two are matter or definition in proportion as
they are near to either. For each of those elements has an end and
is not water or fire in any and every condition of itself, just as
flesh is not flesh nor viscera viscera, and the same is true in a
higher degree with face and hand. What a thing is always determined by
its function: a thing really is itself when it can perform its
function; an eye, for instance, when it can see. When a thing cannot
do so it is that thing only in name, like a dead eye or one made of
stone, just as a wooden saw is no more a saw than one in a picture.
The same, then, is true of flesh, except that its function is less
clear than that of the tongue. So, too, with fire; but its function is
perhaps even harder to specify by physical inquiry than that of flesh.
The parts of plants, and inanimate bodies like copper and silver,
are in the same case. They all are what they are in virtue of a
certain power of action or passion-just like flesh and sinew. But we
cannot state their form accurately, and so it is not easy to tell when
they are really there and when they are not unless the body is
thoroughly corrupted and its shape only remains. So ancient corpses
suddenly become ashes in the grave and very old fruit preserves its
shape only but not its taste: so, too, with the solids that form
from milk.
Now heat and cold and the motions they set up as the bodies are
solidified by the hot and the cold are sufficient to form all such
parts as are the homogeneous bodies, flesh, bone, hair, sinew, and the
rest. For they are all of them differentiated by the various qualities
enumerated above, tension, tractility, comminuibility, hardness,
softness, and the rest of them: all of which are derived from the
hot and the cold and the mixture of their motions. But no one would go
as far as to consider them sufficient in the case of the
non-homogeneous parts (like the head, the hand, or the foot) which
these homogeneous parts go to make up. Cold and heat and their
motion would be admitted to account for the formation of copper or
silver, but not for that of a saw, a bowl, or a box. So here, save
that in the examples given the cause is art, but in the nonhomogeneous
bodies nature or some other cause.
Since, then, we know to what element each of the homogeneous
bodies belongs, we must now find the definition of each of them, the
answer, that is, to the question, 'what is' flesh, semen, and the
rest? For we know the cause of a thing and its definition when we know
the material or the formal or, better, both the material and the
formal conditions of its generation and destruction, and the efficient
cause of it.
After the homogeneous bodies have been explained we must consider
the non-homogeneous too, and lastly the bodies made up of these,
such as man, plants, and the rest.
-THE END-
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