Table of Contents
Previous section |
Next section
7
If a body contains more water than
earth fire only thickens it: if
it contains more earth fire solidifies it. Hence natron and salt and
stone and potter's clay must contain more earth.
The
nature of oil presents the greatest problem. If water
preponderated in it, cold ought to solidify it; if earth
preponderated, then fire ought to do so. Actually neither
solidifies, but both thicken it. The reason is that it is full of
air (hence it floats on the top of water, since air tends to rise).
Cold thickens it by turning the air in it into water, for any
mixture of oil and water is thicker than either. Fire and the lapse of
time thicken and whiten it. The whitening follows on the
evaporation
of any water that may have been in it; the is due to the change of the
air into water as the heat in the oil is dissipated. The effect in
both cases is the same and the cause is the same, but the manner of
its operation is different. Both heat and cold thicken it, but neither
dries it (neither the sun nor cold dries oil), not only because it
is glutinous but because it contains air. Its glutinous nature
prevents it from giving off
vapour and so fire does not dry it or boil
it off.
Those bodies which are made up of earth and water may be
classified according to the preponderance of either. There is a kind
of wine, for instance, which both solidifies and thickens by boiling-I
mean, must. All bodies of this kind lose their water as they That it
is their water may be seen from the fact that the vapour from them
condenses into water when collected. So wherever some sediment is left
this is of the nature of earth. Some of these bodies, as we have said,
are also thickened and dried by cold. For cold not only solidifies but
also dries water, and thickens things by turning air into water.
(Solidifying, as we have said, is a form of drying.) Now those
things that are not thickened by cold, but solidified, belong rather
to water, e.g.. wine, urine, vinegar,
lye, whey. But those things that
are thickened (not by evaporation due to fire) are made up either of
earth or of water and air: honey of earth, while oil contains air.
Milk and blood, too, are made up of both water and earth, though earth
generally predominates in them. So, too, are the liquids out of
which natron and salt are formed; and stones are also formed from some
mixtures of this kind. Hence, if the whey has not been separated, it
burns away if you boil it over a fire. But the earthy element in
milk can also be coagulated by the help of fig-juice, if you boil it
in a certain way as doctors do when they treat it with fig-juice,
and this is how the whey and the cheese are commonly separated.
Whey, once separated, does not thicken, as the milk did, but boils
away like water. Sometimes, however, there is little or no cheese in
milk, and such milk is not nutritive and is more like water. The
case of blood is similar: cold dries and so solidifies it. Those kinds
of blood that do not solidify, like that of the stag, belong rather to
water and are very cold. Hence they contain no fibres: for the
fibres are of earth and solid, and blood from which they have been
removed does not solidify. This is because it cannot dry; for what
remains is water, just as what remains of milk when cheese has been
removed is water. The fact that diseased blood will not solidify is
evidence of the same thing, for such blood is of the nature of serum
and that is
phlegm and water, the nature of the
animal having failed
to get the better of it and digest it.
Some of these bodies are soluble, e.g. natron, some insoluble,
e.g. pottery: of the latter, some, like horn, can be softened by heat,
others, like pottery and stone, cannot. The reason is that opposite
causes have opposite effects: consequently, if solidification is due
to two causes, the cold and the dry, solution must be due to the hot
and the moist, that is, to fire and to water (these being
opposites): water dissolving what was solidified by fire alone, fire
what was solidified by cold alone. Consequently, if any things
happen to be solidified by the action of both, these are least apt
to be soluble. Such a case we find where things have been heated and
are then solidified by cold. When the heat in leaving them has
caused most of the moisture to evaporate, the cold so compacts these
bodies together again as to leave no entrance even for moisture.
Therefore heat does not dissolve them (for it only dissolves those
bodies that are solidified by cold alone), nor does water (for it does
not dissolve what cold solidifies, but only what is solidified by
dry heat). But iron is melted by heat and solidified by cold. Wood
consists of earth and air and is therefore combustible but cannot be
melted or softened by heat. (For the same reason it floats in
water-all except ebony. This does not, for other kinds of wood contain
a preponderance of air, but in black ebony the air has escaped and
so earth preponderates in it.) Pottery consists of earth alone because
it solidified gradually in the process of drying. Water cannot get
into it, for the pores were only large enough to admit of vapour
escaping: and seeing that fire solidified it, that cannot dissolve
it either.
So solidification and melting, their causes, and the kinds of
subjects in which they occur have been described.
8
All this makes it clear that bodies are formed by heat and cold
and that these agents operate by thickening and solidifying. It is
because these qualities fashion bodies that we find heat in all of
them, and in some cold in so far as heat is absent. These qualities,
then, are present as active, and the moist and the dry as passive, and
consequently all four are found in mixed bodies. So water and earth
are the constituents of homogeneous bodies both in plants and in
animals and of metals such as gold, silver, and the rest-water and
earth and their respective exhalations shut up in the compound bodies,
as we have explained elsewhere.
All these mixed bodies are distinguished from one another, firstly
by the qualities special to the various senses, that is, by their
capacities of action. (For a thing is white, fragrant, sonant,
sweet, hot, cold in virtue of a power of acting on sense). Secondly by
other more characteristic affections which express their aptitude to
be affected: I mean, for instance, the aptitude to melt or solidify or
bend and so forth, all these qualities, like moist and dry, being
passive. These are the qualities that differentiate bone, flesh,
sinew, wood, bark, stone and all other homogeneous natural bodies. Let
us begin by enumerating these qualities expressing the aptitude or
inaptitude of a thing to be affected in a certain way. They are as
follows: to be apt or inapt to solidify, melt, be softened by heat, be
softened by water, bend, break, be comminuted, impressed, moulded,
squeezed; to be tractile or non-tractile, malleable or
non-malleable, to be fissile or non-fissile, apt or inapt to be cut;
to be viscous or friable, compressible or incompressible,
combustible or incombustible; to be apt or inapt to give off fumes.
These affections differentiate most bodies from one another. Let us go
on to explain the nature of each of them. We have already given a
general account of that which is apt or inapt to solidify or to
melt, but let us return to them again now. Of all the bodies that
admit of solidification and hardening, some are brought into this
state by heat, others by cold. Heat does this by drying up their
moisture, cold by driving out their heat. Consequently some bodies are
affected in this way by defect of moisture, some by defect of heat:
watery bodies by defect of heat, earthy bodies of moisture. Now
those bodies that are so affected by defect of moisture are
dissolved by water, unless like pottery they have so contracted that
their pores are too small for the particles of water to enter. All
those bodies in which this is not the case are dissolved by water,
e.g. natron, salt, dry mud. Those bodies that solidified through
defect of heat are melted by heat, e.g. ice, lead, copper. So much for
the bodies that admit of solidification and of melting, and those that
do not admit of melting.
The bodies which do not admit of solidification are those which
contain no aqueous moisture and are not watery, but in which heat
and earth preponderate, like honey and must (for these are in a sort
of state of effervescence), and those which do possess some water
but have a preponderance of air, like oil and quicksilver, and all
viscous substances such as pitch and birdlime.
9
Those bodies admit of softening which are not (like ice) made up
of water, but in which earth predominates. All their moisture must not
have left them (as in the case of natron and salt), nor must the
relation of dry to moist in them be incongruous (as in the case of
pottery). They must be tractile (without admitting water) or malleable
(without consisting of water), and the agent in softening them is
fire. Such are iron and horn.
Both of bodies that can melt and of bodies that cannot, some do
and some do not admit of softening in water. Copper, for instance,
which can be melted, cannot be softened in water, whereas wool and
earth can be softened in water, for they can be soaked. (It is true
that though copper can be melted the agent in its case is not water,
but some of the bodies that can be melted by water too such as
natron and salt cannot be softened in water: for nothing is said to be
so affected unless the water soaks into it and makes it softer.)
Some things, on the other hand, such as wool and grain, can be
softened by water though they cannot be melted. Any body that is to be
softened by water must be of earth and must have its pores larger than
the particles of water, and the pores themselves must be able to
resist the action of water, whereas bodies that can be 'melted' by
water must have pores throughout.
(Why is it that earth is both 'melted' and softened by moisture,
while natron is 'melted' but not softened? Because natron is
pervaded throughout by pores so that the parts are immediately divided
by the water, but earth has also pores which do not connect and is
therefore differently affected according as the water enters by one or
the other set of pores.)
Some bodies can be bent or straightened, like the reed or the withy,
some cannot, like pottery and stone. Those bodies are apt to be bent
and straightened which can change from being curved to being
straight and from being straight to being curved, and bending and
straightening consist in the change or
motion to the straight or to
a curve, for a thing is said to be in process of being bent whether it
is being made to assume a convex or a concave shape. So bending is
defined as motion to the convex or the concave without a change of
length. For if we added 'or to the straight', we should have a thing
bent and straight at once, and it is impossible for that which is
straight to be bent. And if all bending is a bending back or a bending
down, the former being a change to the convex, the latter to the
concave, a motion that leads to the straight cannot be called bending,
but bending and straightening are two different things. These, then,
are the things that can, and those that cannot be bent, and be
straightened.
Some things can be both broken and comminuted, others admit only one
or the other. Wood, for instance, can be broken but not comminuted,
ice and stone can be comminuted but not broken, while pottery may
either be comminuted or broken. The distinction is this: breaking is a
division and separation into large parts, comminution into parts of
any size, but there must be more of them than two. Now those solids
that have many pores not communicating with one another are
comminuible (for the limit to their subdivision is set by the
pores), but those whose pores stretch continuously for a long way
are breakable, while those which have pores of both kinds are both
comminuible and breakable.
Some things, e.g. copper and wax, are impressible, others, e.g.
pottery and water, are not. The process of being impressed is the
sinking of a part of the surface of a thing in response to pressure or
a blow, in general to contact. Such bodies are either soft, like
wax, where part of the surface is depressed while the rest remains, or
hard, like copper. Non-impressible bodies are either hard, like
pottery (its surface does not give way and sink in), or liquid, like
water (for though water does give way it is not in a part of it, for
there is a reciprocal change of place of all its parts). Those
impressibles that retain the shape impressed on them and are easily
moulded by the hand are called 'plastic'; those that are not easily
moulded, such as stone or wood, or are easily moulded but do not
retain the shape impressed, like wool or a sponge, are not plastic.
The last group are said to be 'squeezable'. Things are 'squeezable'
when they can contract into themselves under pressure, their surface
sinking in without being broken and without the parts interchanging
position as happens in the case of water. (We speak of pressure when
there is movement and the motor remains in contact with the thing
moved, of impact when the movement is due to the local movement of the
motor.) Those bodies are subject to squeezing which have empty
pores-empty, that is, of the stuff of which the body itself
consists-and that can sink upon the void spaces within them, or rather
upon their pores. For sometimes the pores upon which a body sinks in
are not empty (a wet sponge, for instance, has its pores full). But
the pores, if full, must be full of something softer than the body
itself which is to contract. Examples of things squeezable are the
sponge, wax, flesh. Those things are not squeezable which cannot be
made to contract upon their own pores by pressure, either because they
have no pores or because their pores are full of something too hard.
Thus iron, stone, water and all liquids are incapable of being
squeezed.
Things are tractile when their surface can be made to elongate,
for being drawn out is a movement of the surface, remaining
unbroken, in the direction of the mover. Some things are tractile,
e.g. hair, thongs, sinew, dough, birdlime, and some are not, e.g.
water, stone. Some things are both tractile and squeezable, e.g. wool;
in other cases the two qualities do not coincide; phlegm, for
instance, is tractile but not squeezable, and a sponge squeezable
but not tractile.
Some things are malleable, like copper. Some are not, like stone and
wood. Things are malleable when their surface can be made to move (but
only in part) both downwards and sideways with one and the same
blow: when this is not possible a body is not malleable. All malleable
bodies are impressible, but not all impressible bodies are
malleable, e.g. wood, though on the whole the two go together. Of
squeezable things some are malleable and some not: wax and mud are
malleable, wool is not. Some things are fissile, e.g. wood, some are
not, e.g. potter's clay. A thing is fissile when it is apt to divide
in advance of the instrument dividing it, for a body is said to
split when it divides to a further point than that to which the
dividing instrument divides it and the act of division advances: which
is not the case with cutting. Those bodies which cannot behave like
this are non-fissile. Nothing soft is fissile (by soft I mean
absolutely soft and not relatively: for iron itself may be
relatively soft); nor are all hard things fissile, but only such as
are neither liquid nor impressible nor comminuible. Such are the
bodies that have the pores along which they cohere lengthwise and
not crosswise.
Those hard or soft solids are apt to be cut which do not necessarily
either split in advance of the instrument or break into minute
fragments when they are being divided. Those that necessarily do so
and liquids cannot be cut. Some things can be both split and cut, like
wood, though generally it is lengthwise that a thing can be split
and crosswise that it can be cut. For, a body being divided into
many parts fin so far as its unity is made up of many lengths it is
apt to be split, in so far as it is made up of many breadths it is apt
to be cut.
A thing is viscous when, being moist or soft, it is tractile. Bodies
owe this property to the interlocking of their parts when they are
composed like chains, for then they can be drawn out to a great length
and contracted again. Bodies that are not like this are friable.
Bodies are compressible when they are squeezable and retain the
shape they have been squeezed into; incompressible when they are
either inapt to be squeezed at all or do not retain the shape they
have been squeezed into.
Some bodies are combustible and some are not. Wood, wool, bone are
combustible; stone, ice are not. Bodies are combustible when their
pores are such as to admit fire and their longitudinal pores contain
moisture weaker than fire. If they have no moisture, or if, as in
ice or very green wood, the moisture is stronger than fire, they are
not combustible.
Those bodies give off fumes which contain moisture, but in such a
form that it does not go off separately in vapour when they are
exposed to fire. For vapour is a moist secretion tending to the nature
of air produced from a liquid by the agency of burning heat. Bodies
that give off fumes give off secretions of the nature of air by the
lapse of time: as they perish away they dry up or become earth. But
the kind of secretion we are concerned with now differs from others in
that it is not moist nor does it become
wind (which is a continuous
flow of air in a given direction). Fumes are common secretion of dry
and moist together caused by the agency of burning heat. Hence they do
not moisten things but rather colour them.
The fumes of a woody body are called
smoke. (I mean to include bones
and hair and everything of this kind in the same class. For there is
no name common to all the objects that I mean, but, for all that,
these things are all in the same class by analogy. Compare what
Empedocles says: They are one and the same, hair and leaves and the
thick wings of birds and scales that grow on stout limbs.) The fumes
of fat are a sooty smoke and those of oily substances a greasy
steam. Oil does not boil away or thicken by evaporation because it
does not give off vapour but fumes. Water on the other hand does not
give off fumes, but vapour. Sweet wine does give off fumes, for it
contains fat and behaves like oil. It does not solidify under the
influence of cold and it is apt to burn. Really it is not wine at
all in spite of its name: for it does not taste like wine and
consequently does not inebriate as ordinary wine does. It contains but
little fumigable stuff and consequently is inflammable.
All bodies are combustible that dissolve into ashes, and all
bodies do this that solidify under the influence either of heat or
of both heat and cold; for we find that all these bodies are
mastered by fire. Of stones the precious stone called carbuncle is
least amenable to fire.
Of combustible bodies some are inflammable and some are not, and
some of the former are reduced to coals. Those are called
'inflammable' which produce flame and those which do not are called
'non-inflammable'. Those fumigable bodies that are not liquid are
inflammable, but pitch, oil, wax are inflammable in conjunction with
other bodies rather than by themselves. Most inflammable are those
bodies that give off smoke. Of bodies of this kind those that
contain more earth than smoke are apt to be reduced to coals. Some
bodies that can be melted are not inflammable, e.g. copper; and some
bodies that cannot be melted are inflammable, e.g. wood; and some
bodies can be melted and are also inflammable, e.g. frankincense.
The reason is that wood has its moisture all together and this is
continuous throughout and so it burns up: whereas copper has it in
each part but not continuous, and insufficient in quantity to give
rise to flame. In frankincense it is disposed in both of these ways.
Fumigable bodies are inflammable when earth predominates in them and
they are consequently such as to be unable to melt. These are
inflammable because they are dry like fire. When this dry comes to
be hot there is fire. This is why flame is burning smoke or dry
exhalation. The fumes of wood are smoke, those of wax and frankincense
and such-like, and pitch and whatever contains pitch or such-like
are sooty smoke, while the fumes of oil and oily substances are a
greasy steam; so are those of all substances which are not at all
combustible by themselves because there is too little of the dry in
them (the dry being the means by which the transition to fire is
effected), but burn very readily in conjunction with something else.
(For the fat is just the conjunction of the oily with the dry.) So
those bodies that give off fumes, like oil and pitch, belong rather to
the moist, but those that burn to the dry.
10
Homogeneous bodies differ to touch-by these affections and
differences, as we have said. They also differ in respect of their
smell, taste, and colour.
By homogeneous bodies I mean, for instance, 'metals', gold,
copper, silver, tin, iron, stone, and everything else of this kind and
the bodies that are extracted from them; also the substances found
in animals and plants, for instance, flesh, bones, sinew, skin,
viscera, hair, fibres, veins (these are the elements of which the
non-homogeneous bodies like the face, a hand, a foot, and everything
of that kind are made up), and in plants, wood, bark, leaves, roots,
and the rest like them.
The homogeneous bodies, it is true, are constituted by a different
cause, but the matter of which they are composed is the dry and the
moist, that is, water and earth (for these bodies exhibit those
qualities most clearly). The agents are the hot and the cold, for they
constitute and make concrete the homogeneous bodies out of earth and
water as matter. Let us consider, then, which of the homogeneous
bodies are made of earth and which of water, and which of both.
Of organized bodies some are liquid, some soft, some hard. The
soft and the hard are constituted by a process of solidification, as
we have already explained.
Those liquids that go off in vapour are made of water, those that do
not are either of the nature of earth, or a mixture either of earth
and water, like milk, or of earth and air, like wood, or of water
and air, like oil. Those liquids which are thickened by heat are a
mixture. (Wine is a liquid which raises a difficulty: for it is both
liable to evaporation and it also thickens; for instance new wine
does. The reason is that the word 'wine' is ambiguous and different
'wines' behave in different ways. New wine is more earthy than old,
and for this reason it is more apt to be thickened by heat and less
apt to be congealed by cold. For it contains much heat and a great
proportion of earth, as in Arcadia, where it is so dried up in its
skins by the smoke that you scrape it to drink. If all wine has some
sediment in it then it will belong to earth or to water according to
the quantity of the sediment it possesses.) The liquids that are
thickened by cold are of the nature of earth; those that are thickened
either by heat or by cold consist of more than one element, like oil
and honey, and 'sweet wine'.
Of solid bodies those that have been solidified by cold are of
water, e.g. ice,
snow,
hail,
hoar-frost. Those solidified by heat
are of earth, e.g. pottery, cheese, natron, salt. Some bodies are
solidified by both heat and cold. Of this kind are those solidified by
refrigeration, that is by the privation both of heat and of the
moisture which departs with the heat. For salt and the bodies that are
purely of earth solidify by the privation of moisture only, ice by
that of heat only, these bodies by that of both. So both the active
qualities and both kinds of matter were involved in the process. Of
these bodies those from which all the moisture has gone are all of
them of earth, like pottery or amber. (For amber, also, and the bodies
called 'tears' are formed by refrigeration, like myrrh,
frankincense, gum. Amber, too, appears to belong to this class of
things: the animals enclosed in it show that it is formed by
solidification. The heat is driven out of it by the cold of the
river and causes the moisture to evaporate with it, as in the case
of honey when it has been heated and is immersed in water.) Some of
these bodies cannot be melted or softened; for instance, amber and
certain stones, e.g. the stalactites in caves. (For these stalactites,
too, are formed in the same way: the agent is not fire, but cold which
drives out the heat, which, as it leaves the body, draws out the
moisture with it: in the other class of bodies the agent is external
fire.) In those from which the moisture has not wholly gone earth
still preponderates, but they admit of softening by heat, e.g. iron
and horn.
Now since we must include among 'meltables' those bodies which are
melted by fire, these contain some water: indeed some of them, like
wax, are common to earth and water alike. But those that are melted by
water are of earth. Those that are not melted either by fire or
water are of earth, or of earth and water.
Since, then, all bodies are either liquid or solid, and since the
things that display the affections we have enumerated belong to
these two classes and there is nothing intermediate, it follows that
we have given a complete account of the criteria for distinguishing
whether a body consists of earth or of water or of more elements
than one, and whether fire was the agent in its formation, or cold, or
both.
Gold, then, and silver and copper and tin and lead and glass and
many nameless stone are of water: for they are all melted by heat.
Of water, too, are some wines and urine and vinegar and lye and whey
and serum: for they are all congealed by cold. In iron, horn, nails,
bones, sinews, wood, hair, leaves, bark, earth preponderates. So, too,
in amber, myrrh, frankincense, and all the substances called
'tears', and stalactites, and fruits, such as leguminous plants and
corn. For things of this kind are, to a greater or less degree, of
earth. For of all these bodies some admit of softening by heat, the
rest give off fumes and are formed by refrigeration. So again in
natron, salt, and those kinds of stones that are not formed by
refrigeration and cannot be melted. Blood, on the other hand, and
semen, are made up of earth and water and air. If the blood contains
fibres, earth preponderates in it: consequently its solidifies by
refrigeration and is melted by liquids; if not, it is of water and
therefore does not solidify. Semen solidifies by refrigeration, its
moisture leaving it together with its heat.
Table of Contents
Previous section |
Next section