On the Principle of Cold (12-15)

Furthermore, portions of water will freeze sooner than the spring from which they are drawn, for the air more readily masters the smaller amount. If you will draw from a well cold water in a jar[*] and let it down again into the well in such a way that the jar does not touch the water, but is suspended in the air, and if you wait a short time, you will find that the water has become colder.[*] This is very good evidence that the First Cause of coldness is not water but air. Certainly, none of the great rivers freezes through its entire depth; for the air does not penetrate down into the whole, but merely renders stationary as much as, by contact and proximity, it includes within the range of its coldness. And this is the reason why barbarians[*] do not cross frozen rivers until they have tried them out with foxes: if the ice is not thick, but merely superficial, the foxes perceive this by the sound of the current running underneath and return to the bank. Some even catch fish by weakening and softening the ice with hot water - enough of the ice, at least, to admit their lines; so the cold has no effect at a depth. Yet the water near the surface undergoes so great a change through freezing that ships are crushed by it when it is forced in on itself and squeezed tight, as those relate who recently passed the winter

with Caesar[*] on the Danube. Nevertheless, what happens in our own case is ample testimony: after warm baths and sweats we are cooler, since our bodies are relaxed and porous, so that we take in a good deal of cold along with the air.[*] The same thing happens to water, too: it freezes faster when it has first been heated, thus becoming more susceptible to air; and those who draw off boiling water and suspend it in the air do this, surely, only to secure the admixture of great quantities of air.[*] So now, Favorinus, the argument that attributes the primal force of cold to the air depends on such plausibilities as these.

But the argument which attributes it to water finds in the same way facts to support it; Empedocles[*] says something like this:

Behold the sun, everywhere bright and warm;

And then the rain, to all men dark and cold.

By thus setting cold against hot, as he does dark against bright, he has given us to understand that dark and cold belong to the same substance, as do also bright and hot. And our senses bear witness that darkness is an attribute of water, not of air, since nothing, to put it simply, is blackened by air and everything is by water.[*] For if you throw the whitest wool or the whitest garment into water, it will come out black and it will remain black until the moisture is evaporated by heat or is squeezed out by some sort of wringing or pressure. When a patch of ground is sprinkled, the spots which are covered by the drops turn black, but the rest remains as it was. In fact, of water itself the deepest looks the darkest because there is so much of it, while those parts that lie near the air flash and sparkle[*]; and of the other liquids oil is the most transparent, as containing the most air. A proof of this is its lightness, by reason of which it maintains itself on the surface of all other things, buoyed up by the air.[*] If it is sprinkled upon the waves, it will calm the sea, not because it is so smooth that the winds slip off it, as Aristotle[*] affirmed; but because the waves are dissipated when they are struck by any moist substance. But it is peculiar to oil that it provides light and sight at the bottom since the moist elements are interspersed with air; it is, in fact, not only on the surface that it provides light for those who pass the night at sea; it does so also for sponge-divers[*] below the surface when it is blown out of their mouths. Air, therefore, has no greater proportion of darkness than water has, and it has less cold. Certainly oil, which has more air than any other moist substance, is least cold; and when it freezes, it forms a soft jelly: the air that is intermixed does not permit it to freeze hard. They dip needles, iron clasps, and all delicate artifacts in oil rather than in water, fearing that the water’s excessive frigidity may distort them. It is, in fact, fairer to judge the argument by this evidence than by that of colour, since snow and hail and ice are at their brightest when they are coldest. Moreover, pitch is both hotter and darker than honey.

I am surprised, nevertheless, when those who maintain that the air is cold because it is dark do not perceive that others think it must be hot because it is light. For darkness is not so closely connected and akin to cold as heaviness and stability are; many things, in fact, which have no heat are bright, but nothing cold is buoyant, light, and soaring. Why, the very clouds, as long as they are akin to the substance of air, float aloft; but as soon as they change to moisture, they fall at once and lose their lightness no less than their warmth as coldness grows within them. Contrariwise, when heat supervenes, they reverse the movement again, for their substance begins to soar as soon as it has changed to air.

Nor is the argument from destruction true either; for when anything is destroyed, it does not perish by becoming its opposite, though it does perish by the action of its opposite, as fire, for instance, is changed by water into air. For of water Aeschylus[*] speaks in tragic style, but accurately, as

The riot-quelling justicer of fire.

And when Homer[*] matched Hephaestus against the river and Apollo against Poseidon in the battle, he did it rather as a philosopher than as a poet. And Archilochus[*] expressed himself well on a woman who was of two minds:

With guileful thoughts she bore

In one hand water, in the other fire.

Among the Persians it was the most compelling plea to gain an end, one which would admit no refusal, if the suppliant took fire, stood in a river, and threatened that if he lost his suit, he would drop the fire into the water. Now he got what he asked, but though he did so, he was punished for the threat, on the ground that it was contrary to law and against nature. Again, the familiar proverb that is on everyone’s lips,[*] to mix fire with water, as an example of the impossible, seems to bear witness that water is hostile to fire, which is destroyed by it and so is punished by being extinguished[*]; it is not so affected by air, which, on the contrary, supports fire and welcomes it in its changed form. For if anything into which the thing destroyed changes is its opposite, why will fire, any more than water, seem opposite to air ? For air changes into water by condensation, and into fire by rarefaction just as, on the other hand, water vanishes into air by rarefaction, but into earth by condensation. Now these processes take place, in my opinion, not because these elements are contrary or hostile to one another, but because they are in close affinity and relationship. But my opponents,[*] whichever way they state their case, ruin their proof. Certainly it is perfectly absurd for them to say that water is frozen by air when they have never seen air itself freezing. For clouds, mists, and flecks in the sky are not congelations, but condensations and thickenings of air that is moist and vaporous. But waterless, dry air never admits loss of heat to the point where such a change might occur. There are, in fact, mountains which do not know clouds or dew or mist because their peaks reach a region of pure air that has no humidity at all. From this fact it is especially obvious that it is the condensation and density below that contribute to air the cold, moist element that is found in combination with it.

It is reasonable that the lower portion of large rivers should not freeze; for the upper portion, being frozen, does not transmit the exhalation which is, accordingly, shut in and turned back, and so provides heat for the deep waters. A demonstration of this is the fact that when the ice melts again a great quantity of vapour rises from the waters. This is also the reason why the bodies of animals are warmer in the winter, because the heat is driven inwards by the cold from without and they keep it within them.

Now drawing off water and suspending it in the air[*] not only takes away its warmth, but its coldness also; those, therefore, who want a very cold drink take care not to disturb the snowpacks[*] or the wet matter that is formed from them by compression, for movement expels both heat and cold.

That such a function of cold belongs not to air, but to water, may be demonstrated as follows from a fresh

start. In the first place, it is improbable that air, which lies adjacent to the aether[*] and touches and is touched by the revolving fiery substance, should have a force that is contrary to that of aether. For one thing, it is impossible for two substances whose boundaries touch and are contiguous not to be acted upon by each other - and if acted upon, for the weaker not to be contaminated by the force that resides in the stronger. Nor is it reasonable to suppose that Nature has placed side by side destroyer and victim, as though she were the author of strife and dissension, not of union and harmony. She does, indeed, make use of opposites to constitute the universe; yet she does not employ them without a tempering element, or where they will collide. She disposes them rather so that a space is skipped and an inserted strip duly assigned whereby they will not destroy one another, but may enjoy communication and co-operation. And this strip is occupied by air, suffused as it is through a space under the fire[*] between it and water. It makes distribution both ways and receives contributions from both, being itself neither hot nor cold, but a blending and union of the two. When these are so fused, they meet without injury and the fused matter sends forth or takes to itself the opposing extremes[*] without violence.