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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 vapour （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； condensat