fiery bodies gather…if； I say； he were to ascend thither； and；
having the power to do this； were to abstract particles of fire and
put them in scales and weigh them； and then； raising the balance； were
to draw the fire by force towards the uncongenial element of the
air； it would be very evident that he could compel the smaller mass
more readily than the larger； for when two things are simultaneously
raised by one and the same power； the smaller body must necessarily
yield to the superior power with less reluctance than the larger；
and the larger body is called heavy and said to tend downwards； and
the smaller body is called light and said to tend upwards。 And we
may detect ourselves who are upon the earth doing precisely the same
thing。 For we of separate earthy natures； and sometimes earth
itself； and draw them into the uncongenial element of air by force and
contrary to nature； both clinging to their kindred elements。 But
that which is smaller yields to the impulse given by us towards the
dissimilar element more easily than the larger； and so we call the
former light； and the place towards which it is impelled we call
above； and the contrary state and place we call heavy and below
respectively。 Now the relations of these must necessarily vary；
because the principal masses of the different elements hold opposite
positions； for that which is light； heavy； below or above in one place
will be found to be and become contrary and transverse and every way
diverse in relation to that which is light； heavy； below or above in
an opposite place。 And about all of them this has to be
considered：…that the tendency of each towards its kindred element
makes the body which is moved heavy； and the place towards which the
motion tends below； but things which have an opposite tendency we call
by an opposite name。 Such are the causes which we assign to these
phenomena。 As to the smooth and the rough； any one who sees them can
explain the reason of them to another。 For roughness is hardness
mingled with irregularity； and smoothness is produced by the joint
effect of uniformity and density。
The most important of the affections which concern the whole body
remains to be considered…that is； the cause of pleasure and pain in
the perceptions of which I have been speaking； and in all other things
which are perceived by sense through the parts of the body； and have
both pains and pleasures attendant on them。 Let us imagine the
causes of every affection； whether of sense or not； to be of the
following nature； remembering that we have already distinguished
between the nature which is easy and which is hard to move； for this
is the direction in which we must hunt the prey which we mean to take。
A body which is of a nature to be easily moved； on receiving an
impression however slight； spreads abroad the motion in a circle；
the parts communicating with each other； until at last； reaching the
principle of mind； they announce the quality of the agent。 But a
body of the opposite kind； being immobile； and not extending to the
surrounding region； merely receives the impression； and does not
stir any of the neighbouring parts； and since the parts do not
distribute the original impression to other parts； it has no effect of
motion on the whole animal； and therefore produces no effect on the
patient。 This is true of the bones and hair and other more earthy
parts of the human body； whereas what was said above relates mainly to
sight and hearing； because they have in them the greatest amount of
fire and air。 Now we must conceive of pleasure and pain in this way。
An impression produced in us contrary to nature and violent； if
sudden； is painful； and； again； the sudden return to nature is
pleasant； but a gentle and gradual return is imperceptible and vice
versa。 On the other hand the impression of sense which is most
easily produced is most readily felt； but is not accompanied by
Pleasure or pain； such； for example； are the affections of the
sight； which； as we said above； is a body naturally uniting with our
body in the day…time； for cuttings and burnings and other
affections which happen to the sight do not give pain； nor is there
pleasure when the sight returns to its natural state； but the
sensations are dearest and strongest according to the manner in
which the eye is affected by the object； and itself strikes and
touches it； there is no violence either in the contraction or dilation
of the eye。 But bodies formed of larger particles yield to the agent
only with a struggle； and then they impart their motions to the
whole and cause pleasure and pain…pain when alienated from their
natural conditions； and pleasure when restored to them。 Things which
experience gradual withdrawings and emptyings of their nature； and
great and sudden replenishments； fail to perceive the emptying； but
are sensible of the replenishment； and so they occasion no pain； but
the greatest pleasure； to the mortal part of the soul； as is
manifest in the case of perfumes。 But things which are changed all of
a sudden； and only gradually and with difficulty return to their own
nature； have effects in every way opposite to the former； as is
evident in the case of burnings and cuttings of the body。
Thus have we discussed the general affections of the whole body； and
the names of the agents which produce them。 And now I will endeavour
to speak of the affections of particular parts； and the causes and
agents of them； as far as I am able。 In the first place let us set
forth what was omitted when we were speaking of juices； concerning the
affections peculiar to the tongue。 These too； like most of the other
affections； appear to be caused by certain contractions and dilations；
but they have besides more of roughness and smoothness than is found
in other affections； for whenever earthy particles enter into the
small veins which are the testing of the tongue； reaching to the
heart； and fall upon the moist； delicate portions of flesh…when； as
they are dissolved； they contract and dry up the little veins； they
are astringent if they are rougher； but if not so rough； then only
harsh。 Those of them which are of an abstergent nature； and purge
the whole surface of the tongue； if they do it in excess； and so
encroach as to consume some part of the flesh itself； like potash
and soda； are all termed bitter。 But the particles which are deficient
in the alkaline quality； and which cleanse only moderately； are called
salt； and having no bitterness or roughness； are regarded as rather
agreeable than otherwise。 Bodies which share in and are made smooth by
the heat of the mouth； and which are inflamed； and again in turn
inflame that which heats them； and which are so light that they are
carried upwards to the sensations of the head； and cut all that
comes in their way； by reason of these qualities in them； are all
termed pungent。 But when these same particles； refined by
putrefaction； enter into the narrow veins； and are duly proportioned
to the particles of earth and air which are there； they set them
whirling about one another； and while they are in a whirl cause them
to dash against and enter into one another； and so form hollows
surrounding the particles that enter…which watery vessels of air
（for a film of moisture； sometimes earthy； sometimes pure； is spread
around the air） are hollow spheres of water； and those of them which
are pure； are transparent； and are called bubbles； while those
composed of the earthy liquid； which is in a state of general
agitation and effervescence； are said to boil or ferment…of all
these affections the cause is termed acid。 And there is the opposite
affection arising from an opposite cause； when the mass of entering
particles； immersed in the moisture of the mouth； is congenial to
the tongue； and smooths and oils over the roughness； and relaxes the
parts which are unnaturally contracted； and contracts the parts
which are relaxed； and disposes them all according to their
nature…that sort of remedy of violent affections is pleasant and
agreeable to every man； and has the name sweet。 But enough of this。
The faculty of smell does not admit of differences of kind； for
all smells are of a half formed nature； and no element is so
proportioned as to have any smell。 The veins about the nose are too
narrow to admit earth and water； and too wide to detain fire and
air； and for this reason no one ever perceives the smell of any of
them； but smells always proceed from bodies that are damp； or
putrefying； or liquefying； or evaporating； and are perceptible only in
the intermediate state； when water is changing into air and air into
water； and all of them are either vapor or mist。 That which is passing
out of air into water is mist； and that which is passing from water
into air is vapour； and hence all smells are thinner than water and
thicker than air。 The proof of this is； that when there is any
obstruction to the respiration； and a man draws in his breath by
force； then no smell filters through； but the air without the smell
alone penetra