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Book IV
1
WE have explained that the qualities that constitute the elements
are four, and that their combinations determine the number of the
elements to be four.
Two of the qualities, the hot and the cold, are active; two, the dry
and the moist, passive. We can satisfy ourselves of this by looking at
instances. In every case heat and cold determine, conjoin, and
change things of the same kind and things of different kinds,
moistening, drying, hardening, and softening them. Things dry and
moist, on the other hand, both in isolation and when present
together in the same body are the subjects of that determination and
of the other affections enumerated. The account we give of the
qualities when we define their character shows this too. Hot and
cold we describe as active, for 'congregating' is essentially a
species of 'being active': moist and dry are passive, for it is in
virtue of its being acted upon in a certain way that a thing is said
to be 'easy to determine' or 'difficult to determine'. So it is
clear that some of the qualities are active and some passive.
Next we must describe the operations of the active qualities and the
forms taken by the passive. First of all, true becoming, that is,
natural change, is always the work of these powers and so is the
corresponding natural destruction; and this becoming and this
destruction are found in plants and animals and their parts. True
natural becoming is a change introduced by these powers into the
matter underlying a given thing when they are in a certain ratio to
that matter, which is the passive qualities we have mentioned. When
the hot and the cold are masters of the matter they generate a
thing: if they are not, and the failure is partial, the object is
imperfectly boiled or otherwise unconcocted. But the strictest general
opposite of true becoming is putrefaction. All natural destruction
is on the way to it, as are, for instance, growing old or growing dry.
Putrescence is the end of all these things, that is of all natural
objects, except such as are destroyed by violence: you can burn, for
instance, flesh, bone, or anything else, but the natural course of
their destruction ends in putrefaction. Hence things that putrefy
begin by being moist and end by being dry. For the moist and the dry
were their matter, and the operation of the active qualities caused
the dry to be determined by the moist.
Destruction supervenes when the determined gets the better of the
determining by the help of the environment (though in a special
sense the word putrefaction is applied to partial destruction, when
a thing's
is perverted). Hence everything, except
, is
liable to putrefy; for
, water, and
putrefy, being all of
them matter relatively to fire. The definition of putrefaction is: the
destruction of the peculiar and natural heat in any moist subject by
external heat, that is, by the heat of the environment. So since
lack of heat is the ground of this affection and everything in as
far as it lacks heat is cold, both heat and cold will be the causes of
putrefaction, which will be due indifferently to cold in the
putrefying subject or to heat in the environment.
This explains why everything that putrefies grows drier and ends
by becoming earth or dung. The subject's own heat departs and causes
the natural moisture to evaporate with it, and then there is nothing
left to draw in moisture, for it is a thing's peculiar heat that
attracts moisture and draws it in. Again, putrefaction takes place
less in cold that in hot seasons, for in winter the surrounding air
and water contain but little heat and it has no power, but in
there is more. Again, what is frozen does not putrefy, for its cold is
greater that the heat of the air and so is not mastered, whereas
what affects a thing does master it. Nor does that which is boiling or
hot putrefy, for the heat in the air being less than that in the
object does not prevail over it or set up any change. So too
anything that is flowing or in
is less apt to putrefy than a
thing at rest, for the motion set up by the heat in the air is
weaker than that pre-existing in the object, and so it causes no
change. For the same reason a great quantity of a thing putrefies less
readily than a little, for the greater quantity contains too much
proper fire and cold for the corresponding qualities in the
environment to get the better of. Hence, the
putrefies quickly
when broken up into parts, but not as a whole; and all other waters
likewise. Animals too are generated in putrefying bodies, because
the heat that has been secreted, being natural, organizes the
particles secreted with it.
So much for the nature of becoming and of destruction.
2
We must now describe the next kinds of processes which the qualities
already mentioned set up in actually existing natural objects as
matter.
Of these concoction is due to heat; its species are ripening,
boiling, broiling. Inconcoction is due to cold and its species are
rawness, imperfect boiling, imperfect broiling. (We must recognize
that the things are not properly denoted by these words: the various
classes of similar objects have no names universally applicable to
them; consequently we must think of the species enumerated as being
not what those words denote but something like it.) Let us say what
each of them is. Concoction is a process in which the natural and
proper heat of an object perfects the corresponding passive qualities,
which are the proper matter of any given object. For when concoction
has taken place we say that a thing has been perfected and has come to
be itself. It is the proper heat of a thing that sets up this
perfecting, though external influences may contribute in some
degrees to its fulfilment. Baths, for instance, and other things of
the kind contribute to the digestion of food, but the primary cause is
the proper heat of the body. In some cases of concoction the end of
the process is the nature of the thing-nature, that is, in the sense
of the formal cause and essence. In other cases it leads to some
presupposed state which is attained when the moisture has acquired
certain properties or a certain magnitude in the process of being
broiled or boiled or of putrefying, or however else it is being
heated. This state is the end, for when it has been reached the
thing has some use and we say that concoction has taken place. Must is
an instance of this, and the matter in boils when it becomes purulent,
and tears when they become rheum, and so with the rest.
Concoction ensues whenever the matter, the moisture, is
mastered. For the matter is what is determined by the heat
connatural to the object, and as long as the ratio between them exists
in it a thing maintains its nature. Hence things like the liquid and
solid excreta and ejecta in general are signs of health, and
concoction is said to have taken place in them, for they show that the
proper heat has got the better of the indeterminate matter.
Things that undergo a process of concoction necessarily become
thicker and hotter, for the action of heat is to make things more
compact, thicker, and drier.
This then is the nature of concoction: but inconcoction is an
imperfect state due to lack of proper heat, that is, to cold. That
of which the imperfect state is, is the corresponding passive
qualities which are the natural matter of anything.
So much for the definition of concoction and inconcoction.
3
Ripening is a sort of concoction; for we call it ripening when there
is a concoction of the nutriment in fruit. And since concoction is a
sort of perfecting, the process of ripening is perfect when the
seeds in fruit are able to reproduce the fruit in which they are
found; for in all other cases as well this is what we mean by
'perfect'. This is what 'ripening' means when the word is applied to
fruit. However, many other things that have undergone concoction are
said to be 'ripe', the general character of the process being the
same, though the word is applied by an extension of meaning. The
reason for this extension is, as we explained before, that the various
modes in which natural heat and cold perfect the matter they determine
have not special names appropriated to them. In the case of boils
and
, and the like, the process of ripening is the concoction of
the moisture in them by their natural heat, for only that which gets
the better of matter can determine it. So everything that ripens is
condensed from a spirituous into a watery state, and from a watery
into an earthy state, and in general from being rare becomes dense. In
this process the nature of the thing that is ripening incorporates
some of the matter in itself, and some it rejects. So much for the
definition of ripening.
Rawness is its opposite and is therefore an imperfect concoction
of the nutriment in the fruit, namely, of the undetermined moisture.
Consequently a raw thing is either spirituous or watery or contains
both spirit and water. Ripening being a kind of perfecting, rawness
will be an imperfect state, and this state is due to a lack of natural
heat and its disproportion to the moisture that is undergoing the
process of ripening. (Nothing moist ripens without the admixture of
some dry matter: water alone of liquids does not thicken.) This
disproportion may be due either to defect of heat or to excess of
the matter to be determined: hence the juice of raw things is thin,
cold rather than hot, and unfit for food or drink. Rawness, like
ripening, is used to denote a variety of states. Thus the liquid and
solid excreta and
are called raw for the same reason, for
in every case the word is applied to things because their heat has not
got the mastery in them and compacted them. If we go further, brick is
called raw and so is milk and many other things too when they are such
as to admit of being changed and compacted by heat but have remained
unaffected. Hence, while we speak of 'boiled' water, we cannot speak
of raw water, since it does not thicken. We have now defined
ripening and rawness and assigned their causes.
Boiling is, in general, a concoction by moist heat of the
indeterminate matter contained in the moisture of the thing boiled,
and the word is strictly applicable only to things boiled in the way
of cooking. The indeterminate matter, as we said, will be either
spirituous or watery. The cause of the concoction is the fire
contained in the moisture; for what is cooked in a frying-pan is
broiled: it is the heat outside that affects it and, as for the
moisture in which it is contained, it dries this up and draws it
into itself. But a thing that is being boiled behaves in the
opposite way: the moisture contained in it is drawn out of it by the
heat in the liquid outside. Hence boiled meats are drier than broiled;
for, in boiling, things do not draw the moisture into themselves,
since the external heat gets the better of the internal: if the
internal heat had got the better it would have drawn the moisture to
itself. Not every body admits of the process of boiling: if there is
no moisture in it, it does not (for instance, stones), nor does it
if there is moisture in it but the density of the body is too great
for it-to-be mastered, as in the case of wood. But only those bodies
can be boiled that contain moisture which can be acted on by the
heat contained in the liquid outside. It is true that gold and wood
and many other things are said to be 'boiled': but this is a stretch
of the meaning of the word, though the kind of thing intended is the
same, the reason for the usage being that the various cases have no
names appropriated to them. Liquids too, like milk and must, are
said to undergo a process of 'boiling' when the external fire that
surrounds and heats them changes the savour in the liquid into a given
form, the process being thus in a way like what we have called
boiling.
The end of the things that undergo boiling, or indeed any form of
concoction, is not always the same: some are meant to be eaten, some
drunk, and some are intended for other uses; for instance dyes, too,
are said to be 'boiled'.
All those things then admit of 'boiling' which can grow denser,
smaller, or heavier; also those which do that with a part of
themselves and with a part do the opposite, dividing in such a way
that one portion thickens while the other grows thinner, like milk
when it divides into whey and curd. Oil by itself is affected in
none of these ways, and therefore cannot be said to admit of
'boiling'. Such then is the pfcies of concoction known as 'boiling',
and the process is the same in an artificial and in a natural
instrument, for the cause will be the same in every case.
Imperfect boiling is the form of inconcoction opposed to boiling.
Now the opposite of boiling properly so called is an inconcoction of
the undetermined matter in a body due to lack of heat in the
surrounding liquid. (Lack of heat implies, as we have pointed out, the
presence of cold.) The motion which causes imperfect boiling is
different from that which causes boiling, for the heat which
operates the concoction is driven out. The lack of heat is due
either to the amount of cold in the liquid or to the quantity of
moisture in the object undergoing the process of boiling. Where either
of these conditions is realized the heat in the surrounding liquid
is too great to have no effect at all, but too small to carry out
the process of concocting uniformly and thoroughly. Hence things are
harder when they are imperfectly boiled than when they are boiled, and
the moisture in them more distinct from the solid parts. So much for
the definition and causes of boiling and imperfect boiling.
Broiling is concoction by dry foreign heat. Hence if a man were to
boil a thing but the change and concoction in it were due, not to
the heat of the liquid but to that of the fire, the thing will have
been broiled and not boiled when the process has been carried to
completion: if the process has gone too far we use the word 'scorched'
to describe it. If the process leaves the thing drier at the end the
agent has been dry heat. Hence the outside is drier than the inside,
the opposite being true of things boiled. Where the process is
artificial, broiling is more difficult than boiling, for it is
difficult to heat the inside and the outside uniformly, since the
parts nearer to the fire are the first to get dry and consequently get
more intensely dry. In this way the outer pores contract and the
moisture in the thing cannot be secreted but is shut in by the closing
of the pores. Now broiling and boiling are artificial processes, but
the same general kind of thing, as we said, is found in nature too.
The affections produced are similar though they lack a name; for art
imitates nature. For instance, the concoction of food in the body is
like boiling, for it takes place in a hot and moist medium and the
agent is the heat of the body. So, too, certain forms of indigestion
are like imperfect boiling. And it is not true that animals are
generated in the concoction of food, as some say. Really they are
generated in the excretion which putrefies in the lower belly, and
they ascend afterwards. For concoction goes on in the upper belly
but the excretion putrefies in the lower: the reason for this has been
explained elsewhere.
We have seen that the opposite of boiling is imperfect boiling:
now there is something correspondingly opposed to the species of
concoction called broiling, but it is more difficult to find a name
for it. It would be the kind of thing that would happen if there
were imperfect broiling instead of broiling proper through lack of
heat due to deficiency in the external fire or to the quantity of
water in the thing undergoing the process. For then we should get
too much heat for no effect to be produced, but too little for
concoction to take place.
We have now explained concoction and inconcoction, ripening and
rawness, boiling and broiling, and their opposites.
4
We must now describe the forms taken by the passive qualities the
moist and the dry. The elements of bodies, that is, the passive
ones, are the moist and the dry; the bodies themselves are
compounded of them and whichever predominates determines the nature of
the body; thus some bodies partake more of the dry, others of the
moist. All the forms to be described will exist either actually, or
potentially and in their opposite: for instance, there is actual
melting and on the other hand that which admits of being melted.
Since the moist is easily determined and the dry determined with
difficulty, their relation to one another is like that of a dish and
its condiments. The moist is what makes the dry determinable, and each
serves as a sort of glue to the other-as
Empedocles said in his poem
on Nature, 'glueing meal together by means of water.' Thus the
determined body involves them both. Of the elements earth is
especially representative of the dry, water of the moist, and
therefore all determinate bodies in our world involve earth and water.
Every body shows the quality of that element which predominates in it.
It is because earth and water are the material elements of all
bodies that animals live in them alone and not in air or fire.
Of the qualities of bodies hardness and softness are those which
must primarily belong to a determined thing, for anything made up of
the dry and the moist is necessarily either hard or soft. Hard is that
the surface of which does not yield into itself; soft that which
does yield but not by interchange of place: water, for instance, is
not soft, for its surface does not yield to pressure or sink in but
there is an interchange of place. Those things are absolutely hard and
soft which satisfy the definition absolutely, and those things
relatively so which do so compared with another thing. Now
relatively to one another hard and soft are indefinable, because it is
a matter of degree, but since all the objects of sense are
determined by reference to the faculty of sense it is clearly the
relation to touch which determines that which is hard and soft
absolutely, and touch is that which we use as a standard or mean. So
we call that which exceeds it hard and that which falls short of it
soft.
5
A body determined by its own boundary must be either hard or soft;
for it either yields or does not.
It must also be concrete: or it could not be so determined. So since
everything that is determined and solid is either hard or soft and
these qualities are due to concretion, all composite and determined
bodies must involve concretion. Concretion therefore must be
discussed.
Now there are two causes besides matter, the agent and the quality
brought about, the agent being the efficient cause, the quality the
formal cause. Hence concretion and disaggregation, drying and
moistening, must have these two causes.
But since concretion is a form of drying let us speak of the
latter first.
As we have explained, the agent operates by means of two qualities
and the patient is acted on in virtue of two qualities: action takes
place by means of heat or cold, and the quality is produced either
by the presence or by the absence of heat or cold; but that which is
acted upon is moist or dry or a compound of both. Water is the element
characterized by the moist, earth that characterized by the dry, for
these among the elements that admit the qualities moist and dry are
passive. Therefore cold, too, being found in water and earth (both
of which we recognize to be cold), must be reckoned rather as a
passive quality. It is active only as contributing to destruction or
incidentally in the manner described before; for cold is sometimes
actually said to burn and to warm, but not in the same way as heat
does, but by collecting and concentrating heat.
The subjects of drying are water and the various watery fluids and
those bodies which contain water either foreign or connatural. By
foreign I mean like the water in wool, by connatural, like that in
milk. The watery fluids are wine, urine, whey, and in general those
fluids which have no sediment or only a little, except where this
absence of sediment is due to viscosity. For in some cases, in oil and
pitch for instance, it is the viscosity which prevents any sediment
from appearing.
It is always a process of heating or cooling that dries things,
but the agent in both cases is heat, either internal or external.
For even when things are dried by cooling, like a garment, where the
moisture exists separately it is the internal heat that dries them. It
carries off the moisture in the shape of
(if there is not too
much of it), being itself driven out by the surrounding cold. So
everything is dried, as we have said, by a process either of heating
or cooling, but the agent is always heat, either internal or external,
carrying off the moisture in vapour. By external heat I mean as
where things are boiled: by internal where the heat breathes out and
takes away and uses up its moisture. So much for drying.
6
Liquefaction is, first, condensation into water; second, the melting
of a solidified body. The first, condensation, is due to the cooling
of vapour: what melting is will appear from the account of
solidification.
Whatever solidifies is either water or a mixture of earth and water,
and the agent is either dry heat or cold. Hence those of the bodies
solidified by heat or cold which are soluble at all are dissolved by
their opposites. Bodies solidified by the dry-hot are dissolved by
water, which is the moist-cold, while bodies solidified by cold are
dissolved by fire, which is hot. Some things seem to be solidified
by water, e.g. boiled honey, but really it is not the water but the
cold in the water which effects the solidification. Aqueous bodies are
not solidified by fire: for it is fire that dissolves them, and the
same cause in the same relation cannot have opposite effects upon
the same thing. Again, water solidifies owing to the departure of
heat; so it will clearly be dissolved by the entry into it of heat:
cold, therefore, must be the agent in solidifying it.
Hence aqueous bodies do not thicken when they solidify; for
thickening occurs when the moisture goes off and the dry matter
comes together, but water is the only liquid that does not thicken.
Those bodies that are made up of both earth and water are solidified
both by fire and by cold and in either case are thickened. The
operation of the two is in a way the same and in a way different. Heat
acts by drawing off the moisture, and as the moisture goes off in
vapour the dry matter thickens and collects. Cold acts by driving
out the heat, which is accompanied by the moisture as this goes off in
vapour with it. Bodies that are soft but not liquid do not thicken but
solidify when the moisture leaves them, e.g. potter's clay in
process of baking: but those mixed bodies that are liquid thicken
besides solidifying, like milk. Those bodies which have first been
thickened or hardened by cold often begin by becoming moist: thus
potter's clay at first in the process of baking steams and grows
softer, and is liable to distortion in the ovens for that reason.
Now of the bodies solidified by cold which are made up both of earth
and water but in which the earth preponderates, those which solidify
by the departure of heat melt by heat when it enters into them
again; this is the case with frozen mud. But those which solidify by
refrigeration, where all the moisture has gone off in vapour with
the heat, like iron and horn, cannot be dissolved except by
excessive heat, but they can be softened-though manufactured iron does
melt, to the point of becoming fluid and then solidifying again.
This is how steel is made. The dross sinks to the bottom and is
purged away: when this has been done often and the metal is pure we
have steel. The process is not repeated often because the purification
of the metal involves great waste and loss of weight. But the iron
that has less dross is the better iron. The stone pyrimachus, too,
melts and forms into drops and becomes fluid; after having been in a
fluid state it solidifies and becomes hard again. Millstones, too,
melt and become fluid: when the fluid mass begins to solidify it is
black but its consistency comes to be like that of lime. and earth,
too
Of the bodies which are solidified by dry heat some are insoluble,
others are dissolved by liquid. Pottery and some kinds of stone that
are formed out of earth burnt up by fire, such as millstones, cannot
be dissolved. Natron and salt are soluble by liquid, but not all
liquid but only such as is cold. Hence water and any of its
varieties melt them, but oil does not. For the opposite of the dry-hot
is the cold-moist and what the one solidified the other will dissolve,
and so opposites will have opposite effects.
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