The Senses

What do we mean that “fire is hot?”

Fire has a dividing or cutting power on our bodies. We all feel that fire is sharp. We may further consider:

• the fineness of the sides of fire
• the sharpness of the angles of fire
• the smallness of the particles of fire, and
• the swiftness of the motion of fire

All this makes the action of fire violent and sharp, so that it cuts whatever it meets.

The original shape of fire (i.e. the pyramid), more than any other form, has a dividing power which cuts our bodies into small pieces (Kepmatizei).

It naturally produces that affection called ‘heat’. Hence, the origin of the name (thepmos, Kepma).

The larger particles of moisture which surround the body, enter in and drive out the lesser. But these are unable to take their places. So they compress the moist principle in us.

This from being unequal and disturbed, is forced by them into a state of rest, which is due to equability and compression.

But things which are contracted contrary to nature are by nature at war, and force themselves apart.

• To this war and convulsion, we give the name of “shivering” and “trembling”.
• The affection and the cause of the affection are both called “cold”.

That is called hard to which our flesh yields, and soft which yields to our flesh; and things are also termed hard and soft relatively to one another.

That which yields has a small base; but that which rests on quadrangular bases is firmly posed and belongs to the class which offers the greatest resistance; so too does that which is the most compact and therefore most repellent.

The nature of the light and the heavy will be best understood when examined in connexion with our notions of above and below.

It is wrong to suppose that the universe is parted into 2 regions, separate from and opposite to each other, the one a lower to which all things tend which have any bulk, and an upper to which things only ascend against their will.

The universe has a sphere shape. All the extremities are equidistant from the centre, and are equally extremities.

The centre, which is equidistant from them, is equally to be regarded as the opposite of them all.

The centre of the universe is just the centre and nothing else.

The circumference is not the centre, and has in no one part of itself a different relation to the centre from what it has in any of the opposite parts.

It is in every direction similar. How can one give to it names which imply opposition?

For if there were any solid body in equipoise at the centre of the universe, there would be nothing to draw it to this extreme rather than to that, for they are all perfectly similar.

If a person were to go around the world in a circle, he would often, when standing at the antipodes of his former position, speak of the same point as above and below; for, as I was saying just now, to speak of the whole which is in the form of a globe as having one part above and another below is not like a sensible man.

The reason why these names are used, and the circumstances under which they are ordinarily applied by us to the division of the heavens, may be elucidated by the following supposition:

If a person stood where the fire of the universe gathered [star?] and weighed the abstract particles of fire by raising the balance and drawing the fire by force towards the uncongenial element of the air, then he could compel the smaller mass more readily than the larger.

The larger body is called heavy and tends downwards. The smaller body is called light and tends upwards.

We on earth do precisely the same thing.

We often 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 the smaller yields to the impulse given by us towards the dissimilar element more easily than the larger. We call the former “light”. We call “above” as the place where it goes. The contrary state we call heavy. We call its destination as “below”.

The relations of these 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.

The tendency of each towards its kindred element makes the body “heavy” and its destination as “below”. The things which have an opposite tendency we call by an opposite name.

The most important of the affections which concern the whole body is the cause of pleasure and pain. 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 naturally easily moved spreads abroad the motion in a circle upon receiving any impression. Its parts communicate with each other until finally they reaching the principle of mind and announce the quality of the agent.

But an immobile body merely receives the impression. It does not stir any of the neighbouring parts and so the parts do not distribute the original impression to other parts. It thus has no effect of motion on the whole animal. It 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 clearest 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.

Taste, 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 instruments 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.

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.

This is why 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. All of them are either vapour 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 penetrates. Wherefore the varieties of smell have no name, and they have not many, or definite and simple kinds;

but they are distinguished only as painful and pleasant, the one sort irritating and disturbing the whole cavity which is situated between the head and the navel, the other having a soothing influence, and restoring this same region to an agreeable and natural condition.

Hearing is a third kind of sense.

Sound is a blow which passes through the ears, and is transmitted by means of the air, the brain, and the blood, to the soul, and that hearing is the vibration of this blow, which begins in the head and ends in the region of the liver.

The sound which moves swiftly is acute, and the sound which moves slowly is grave, and that which is regular is equable and smooth, and the reverse is harsh.

A great body of sound is loud, and a small body of sound the reverse. Respecting the harmonies of sound I must hereafter speak.