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The law of earthquakes
Above and below the earth are windy caverns on all sides. It bears in its bosom many lakes and many pools and cliffs and sheer rocks;
- Earthquakes. The earth underneath has caverns and streams and rocks. and that many rivers hidden beneath the back of the earth roll on amain their waves and submerged stones. For clear fact demands n that it should be in all parts like itself. When these things then are placed and linked together beneath it, the earth above trembles, shaken by great falling masses, when beneath time has caused huge caverns to fall in; nay, indeed, whole mountains fall,(a) When some cavern falls in, an earthquake is caused, and at the great sudden shock tremblings creep abroad thence far and wide. And with good reason, since whole houses by the roadside tremble when shaken by a wagon of no great weight, and rock none the less, whenever a stone in the road jolts on the iron circles of the wheels on either side. 1 It comes to pass too,just as houses are rocked by passing wagons, or the land by an avalanche falling into a lake, like water rocking in a vessel. when a vast mass of soil, loosened by age from the earth, rolls down into huge wide pools of water, that the earth too tosses and sways beneath the wave of water; even as a vessel sometimes cannot stand still, unless the liquid within has ceased to toss with unsteady wave.
(b) An earthquake may be caused by a great subterranean wind blowing violently in one direction. And yet men will not believe in the ultimate destruction of the earth, when it is only the alteration of the wind which restores equilibrium.Moreover, when the wind gathering throughout the cavernous places of the earth blows strong from one point, and with all its weight presses on the lofty caves with mighty strength, the earth leans over to where the swooping force of the wind presses it. Then the houses that are built up upon the earth, yea, the more they are severally raised towards the sky, bend over in suspense, tottering towards the same quarter, and the timbers driven forward hang out ready to fall. And yet men fear to believe that a time of destruction and ruin awaits the nature of the great world, even when they see so great a mass of earth bowing to its fall. Why, unless the winds breathed in again, no force could put a curb on things or avail to pull them back from destruction as they fell. As it is, because turn by turn they breathe in and then grow violent, because, as it were, they rally and charge again and then are driven back and give ground, for this reason the earth more often threatens a fall than brings it to pass; for it leans over and then sways back again, and after falling forward recovers its position to a steady poise. In this way, then, the whole building rocks, the top more than the middle, the middle more than the bottom, the bottom but a very little.
(c) Sometimes the imprisoned air bursts forth, making a great chasm:There is this cause, too, of that same great shaking, when suddenly wind and some exceeding great force of air, gathering either from without or within the earth itself, have hurled themselves into the hollow places of the earth, and there first rage among the great caves in turmoil, and rise, carried on in a whirl; and when afterwards the moving force driven forth bursts out and at the same time cleaves the earth and causes a huge chasm. Even as it came to pass at Sidon in Syria, and as was the case at Aegium in Peloponnese, cities overthrown by this issue of air and the quaking of the earth which arose. And besides many walled towns have fallen through great movements on land, and many cities have sunk down deep into the sea, inhabitants and all.or remaining imprisoned, causes the earth to shudder. And even if it does not burst forth, yet the very impulse of the air and the fierce force of the wind are spread, like a fit of shivering, throughout the riddling passages of the earth, and thereby induce a trembling: even as cold, when it comes deep into our members, shakes them against their will and constrains them to tremble and to move. So men quiver with anxious terror throughout the cities, they fear the houses above, they dread the hollow places beneath, lest the nature of the earth should break them open all at once, and lest torn asunder she should open wide her maw, and, tumbled all together, desire to fill it with her own falling ruins.It is a lesson that the whole world may thus be destroyed. Let them then believe as they will that heaven and earth will be indestructible, entrusted to some everlasting protection; and yet from time to time the very present force of danger applies on some side or other this goad of fear, lest the earth, snatched away suddenly from beneath their feet be carried into the abyss, and the sum of things, left utterly without foundation, follow on, and there be a tumbling wreck of the whole world.
Why does not the sea increase? 1 First of all they wonder that nature does not make the sea bigger, since there comes into it so great a downpour of water, yea, all the streams from every quarter. Add, if you will, the shifting showers and the scudding storms, which bespatter and drench all seas and lands; add too its own springs; yet compared to the sum of the sea all these things will scarce be equal to the increase of a single drop;(a) Because all that is added to it is but a drop in the ocean; (b) because much water is drawn off by sun, therefore it is the less strange that the great sea does not increase. Moreover, the sun draws off a great part by his heat. For verily we see the sun with its blazing rays dry clothes wringing with moisture; and yet we see many oceans spread wide beneath earth’s level. Therefore, although from each single place the sun sucks up but a small part of moisture from the level sea; yet in so great a space it will draw largely from the waves. Then again,by wind, the winds too can lift a great part of moisture as they sweep the level seas, since very often we see roads dried by the wind in a single night, and the soft mud harden into crusts.and by clouds; Moreover, I have shown that the clouds too lift up much moisture taken in from the great level of ocean, and scatter it broadcast over all the circle of lands, when it rains on the earth and the winds carry on the clouds.or (c) oozes into the earth. Lastly, since the earth is formed of porous body, and is continuous, surrounding on all sides the shores of the sea, it must needs be that, just as the moisture of water passes into the sea from the lands, it likewise filters through into the land from the salt sea levels; for the brine is strained through, and the substance of moisture oozes back and all streams together at the fountain-head of rivers, and thence comes back over the lands with freshened current, where the channel once cleft has brought down the waters in their liquid march.
The eruption of Etna.Now what is the reason that through the jaws of Mount Etna flames sometimes breathe forth in so great a hurricane, I will unfold. For indeed the flaming storm gathered with no moderate force of destruction and ruled tyrant through the fields of the Sicilians and turned to itself the gaze of neighbouring nations, when they saw all the quarters of the heavens smoke and sparkle, and filled their breasts with shuddering anxiety for what new change nature might be planning.
Remember the vastness of the universe.Herein you must look far and deep and take a wide view to every quarter, that you may remember that the sum of things is unfathomable, and see how small, how infinitely small a part of the whole sum is one single heaven—not so large a part, as is a single man of the whole earth. And if you have this duly before you and look clearly at it and see it clearly, you would cease to wonder at many things. For does any of us wonder,Just as many diseases may come to the body, if a man has caught in his limbs a fever gathering with burning heat, or any other painful disease in his members? For a foot will swell suddenly, often a sharp pain seizes on the teeth or makes its way right into the eyes; the holy fire n breaks out and creeping about in the body burns any part which it has seized, and crawls through the limbs, because, as we may be sure, there are seeds of many things, and this earth and heaven has enough disease and malady, from which the force of measureless disease might avail to spread abroad.so the infinite can supply innumerable seeds of malady to heaven and earth. So then we must suppose that out of the infinite all things are supplied to the whole heaven and earth in number enough that on a sudden the earth might be shaken and moved, and a tearing hurricane course over sea and land, the fire of Etna well forth, and the heaven be aflame. For that too comes to pass, and the quarters of heaven blaze, and there are rainstorms gathering in heavier mass, when by chance the seeds of the waters have so arranged themselves.The eruption seems ‘gigantic’, but so always does the greatest thing of its kind which we have seen. ‘Nay, but the stormy blaze of this fire is exceeding gigantic.’ So, too, be sure, is the river which is the greatest seen by a man, who has never before seen any greater: so a tree or a man may seem gigantic, and in every kind of thing, the greatest that each man has seen, he always imagines gigantic, and yet all of them together, yea, with heaven and earth and sea besides, are nothing to the whole sum of the universal sum.
The eruption is caused because wind gathers in subterranean caverns,But now in what ways that flame is suddenly excited and breathes abroad from out the vast furnaces of Etna, I will unfold. First of all the nature of the whole mountain is hollow beneath, resting everywhere on caverns of basalt. Moreover, in all the caves there is wind and air. For air becomes wind, when
it is set in motion and aroused. When it has grown hot,heats itself and all around it, and then bursts out. and as it rages has heated all the rocks and the earth around wherever it touches them, and has struck out from them a fire hot with swift flames, it rises up and so drives itself forth on high straight through the mountain’s jaws. And so it carries its heat far, and afar it scatters the ash and rolls on a smoke with thick murky darkness, and all the while hurls out rocks of marvellous weight; for you must not doubt that this is the stormy force of air.There are also passages from the neighbouring sea, by which blasts of wind enter in. Moreover, in great part the sea makes its waves break and sucks in its tide at the roots of that mountain. From this sea caves stretch underneath right to the deep jaws of the mountain. By this path we must admit that
For some things we must mention several possible causes, one of which will be true in the given case.Some things there are, too, not a few, for which to tell one cause is not enough; we must give more, one of which is yet the actual cause; just as if you yourself were to see the lifeless body of a man lying before you, it would be right that you should name all causes of death, in order that the one cause of that man’s death might be told. For you could not prove that he had perished by the sword or of cold, or by disease or perchance by poison, but we know that it was something of this sort which was his fate. Likewise, we can say the same in many cases.
The rise of the Nile may be caused (a) by the north winds opposing its stream;The Nile, the river of all Egypt, alone in the world rises, as summer comes, and overflows the plains. It waters Egypt often amid the hot season, either because in summer the north winds, which at that time are said to be the etesian winds, are dead against its mouths; blowing against its stream they check it, and driving the waters upwards fill the channel and make it stop. For without doubt these blasts, which are started from the chill constellations of the pole are driven full against the stream. The river comes from the south out of the quarter where heat is born, rising among the black races of men of sunburnt colour far inland in the region of mid-day.(b) by a sand-barrier choking the stream; It may be too that a great heaping up of sand may choke up the mouths as a bar against the opposing waves, when the sea, troubled by the winds, drives the sand within; and in this manner it comes to pass that the river has less free issue, and the waves likewise a less easy downward flow. It may be, too,(c) by excessive rain in the interior; perhaps that rains occur more at its source at that season, because the etesian blasts of the north winds then drive all the clouds together into those quarters. And, we may suppose, when they have come together driven towards the region of mid-day, there at last the clouds, thrust together upon the high mountains,(d) by the melting of snow on the mountains. are massed and violently pressed. Perchance it swells from deep among the high mountains of the Ethiopians, where the sun, traversing all with his melting rays, forces the white snows to run down into the plains.
Avernian spots; so-called as they are fatal to birds.Come now, I will unfold to you with what nature are endowed all Avernian places and lakes. First of all, in that they are called by the name Avernian, n that is given them from the fact, because they are harmful to all birds, in that, when they have come right over those spots in their flight, forgetting the oarage of their wings, they slack their sails, and fall headlong, drooping with languid neck to earth, if by chance the nature of the spots so determines it, or into the water, if by chance the lake of Avernus spreads beneath them.Such as lake Avernus, That spot is by Cumae, where mountains smoke, choked with biting sulphur and enriched with hot springs. There is too a spot within the walls of Athens, on the very summit of the citadel, by the temple of Pallas Tritonis,a spot by the Parthenon, the life-giver, whither croaking crows never steer their bodies on the wing, not even when the altars smoke with offerings. So surely do they fly, not in truth from the fierce wrath of Pallas, because of their vigil, n as the poets of the Greeks have sung, but the nature of the spot of its own force accomplishes the task.and a place in Syria. In Syria, too, it is said that there is likewise a spot to be seen, where, as soon as even fourfooted beasts have set foot, its natural force constrains them to fall heavily, as though they were on a sudden slaughtered to the gods of the dead.All owe their power to natural causes, and are not gates of hell. Yet all these things are brought about by a natural law, and it is clearly seen from what causes to begin with they come to be; lest by chance 1 the gateway of Orcus should be thought to be in these regions; and thereafter we should by chance believe that the gods of the dead lead the souls below from this spot to the shores of Acheron; even as stags of winged feet are often thought by their scent to drag from their lairs the races of crawling serpents. And how far removed this is from true reason, now learn; for now I will try to tell of the true fact.
Earth contains the elements of all things, both good and bad.First of all I say, what I have often said before as well, that in the earth there are shapes of things of every kind; many which are good for food, helpful to life, and many which can induce diseases and hasten death. And that for different animals different things are suited for the purpose of life, I have shown before, because their nature and texture and the shapes of their first-beginnings are unlike, the one to the other.And among them many things noxious to each of the senses. Many things which are harmful pass through the ears, many which are dangerous and rough to draw in 2 find their way even through the nostrils, nor are there a few which should be avoided by the touch, yea, and shunned by the sight, or else are bitter to the taste.
Many such exhalations are poisonous to man. Trees.Next we may see how many things are for man of a sensation keenly harmful, and are nauseous and noxious; first, certain trees are endowed with a shade so exceeding noxious, that often they cause an aching of the head, if one has lain beneath them, stretched upon the grass. There is, too, a tree on the great mountains of Helicon, which is wont to kill a man with the noisome scent of its flower. We may be sure that these things all grow in this way from the earth, because the earth contains in itself many seeds of many things, mingled in many ways, and gives them forth singled out.An extinguished candle to an epileptic. Again, a light but newly extinguished at night, when it meets the nostrils with its pungent smell, at once puts to sleep a man who is wont through disease to fall down and foam at the mouth. And a woman will fall back asleep with the heavy scent of castor,Castor to a woman. and her gay-coloured work slips from her delicate hands, if she has smelt it at the time when she has her monthly discharge. And many other things too slacken the drooping members throughout the frame,A hot bath after a meal. and make the soul totter within its abode. Once again, if you dally in the hot bath when you are too full, how easily it comes to pass often that you fall down, as you sit on the stool in the middle of the boiling water.Charcoal. And how easily the noxious force and smell of charcoal finds its way into the brain, unless we have taken water beforehand.Wine to the feverish. And when the burning fever has seized and subdued the limbs, 1 then the smell of wine is like a slaughtering blow. Do you not see, too, sulphur produced in the very earth and pitch harden into crusts of a noisome scent?Mines to those who work in them. and again, when men are following up the veins of gold and silver, probing with the pick deep into the hidden parts of earth, what stenches Scaptensula n breathes out underground? And what poison gold mines may exhale! how strange they make men’s faces, how they change their colour! Have you not seen or heard how they are wont to die in a short time and how the powers of life fail those, whom the strong force of necessity imprisons in such work? All these effluences then earth sends steaming forth, and breathes them out into the open and the clear spaces of heaven.
So these Avernian spots too must needs send up some fume deadly to the birds,Similarly these spots give out an exhalation, which first stops the birds, and then kills them when they fall. which rises from the earth into the air, so that it poisons the expanse of heaven in a certain quarter; and at the very moment when the bird is carried thither on its wings, it is checked there, seized by the secret poison, so that it tumbles straight down on the spot, where the effluence has its course. And when it has fallen into it, there the same force of the effluence takes away the remnant of life out of all its limbs. For verily first of all it causes a kind of dizzy seething in the birds: afterwards it comes to pass that, when they have fallen right into the sources of the poison, there they must needs vomit forth their life as well, because there is great store of poison all around them.
It may be that the effluence dispels the air, and so the birds fall in a vacuum.It may happen, too, sometimes that this force and effluence of Avernus dispels all the air that is situate between the birds and the ground, so that there is left here an almost empty space. And when the birds in their flight have come straight over this place, on a sudden the lifting force of their pinions is crippled and useless, and all the effort of their wings fails on either side. And then, when they cannot support themselves or rest upon their wings, of course nature constrains them to sink by their weight to the ground, and lying in death in what is now almost empty void, they scatter abroad their soul through all the pores of their body 1 moreover,6. Wells are cold in summer, because earth gives out its heat into the air, and warm in winter, because it sends its heat into the wells. The fountain of Ammon grows cold in the day and warm at night for exactly similar reasons, the water in wells becomes colder in summer, because the earth grows porous with the heat, and if by chance it has any seeds of heat of its own, it sends them abroad into the air. The more then earth is exhausted of its heat, the colder too becomes the moisture which is hidden in the earth. Moreover, when all the earth is hard pressed with cold, and contracts and, as it were, congeals, of course it comes to pass that, as it contracts, it squeezes out into the wells any heat it bears in itself.
There is said to be near the shrine of Ammon n a fountain, cold in the daylight and warm in the night time. At this fountain men marvel overmuch, and think that it is made to boil in haste by the fierceness of the sun beneath the earth, when night has shrouded earth in dreadful darkness. But this is exceeding far removed from true reasoning. For verily, when the sun, touching the uncovered body of the water, could not make it warm on the upper side, though its light in the upper air enjoys heat so great, how could it beneath the earth with its body so dense boil the water and fill it with warm heat? and that when it can scarcely with its blazing rays make its hot effluence pierce through the walls of houses. What then is the reason? We may be sure, because the ground is rarer and warmer around the fountain than the rest of the earth, and there are many seeds of fire near the body of the water. Therefore, when night covers the earth with the shadows that bring the dew, straightway the earth grows cold deep within and contracts. By this means it comes to pass that, as though it were pressed by the hand, it squeezes out into the fountain all the seeds of fire it has, which make warm the touch and vapour of the water. Then when the rising sun has parted asunder the ground with his rays, and has made it rarer, as his warm heat grows stronger, the first-beginnings of fire pass back again into their old abode, and all the heat of the water retires into the earth. For this cause the fountain becomes cold in the light of day.also because the sun’s heat breaks up the waters and releases the heat in them. Moreover, the moisture of the water is buffeted by the sun’s rays, and in the light grows rarer through the throbbing heat; therefore it comes to pass that it loses all the seeds of fire that it has; just as often it gives out the frost that it contains in itself, and melts the ice and loosens its bindings.
The cold spring, over which torches catch fire, owes its power to seeds of fire, which shoot up separately through the water and unite in flame on the torch.There is also a cold spring, over which if tow be held, it often straightway catches fire and casts out a flame, and a torch in like manner is kindled and shines over the waters, wherever, as it floats, it is driven by the breezes. Because, we may be sure, there are in the water very many seeds of heat, and it must needs be that from the very earth at the bottom bodies of fire rise up through the whole spring, and at the same time are breathed forth and issue into the air, yet not so many of them that the spring can be made hot. Moreover, a force constrains them suddenly to burst forth through the water scattered singly, and then to enter into union up above.It is like springs of fresh water in the sea. Even as there is a spring within the sea at Aradus, n which bubbles up with fresh water and parts the salt waters asunder all around it; and in many other spots too the level sea affords a welcome help to thirsty sailors, because amid the salt it vomits forth fresh water. So then those seeds are able to burst out through that spring, and to bubble out into the tow; and when they gather together or cling to the body of the torch readily they blaze out all at once, because the tow and torches too have many seeds of hidden fire in themselves.Observe how the wick catches before it touches the flame. Do you not see too, when you move a wick just extinguished near a night-lamp, that it is kindled before it has touched the flame, and a torch in like manner? And many other things as well are touched first by the mere heat and blaze out at a distance, before the fire soaks them close at hand. This then we must suppose comes to pass in that spring too.
- The magnet, and how it holds its chain of rings suspended.For what follows, I will essay to tell by what law of nature it comes to pass that iron can be attracted by the stone which the Greeks call the magnet, from the name of its native place, because it has its origin within the boundaries of its native country, the land of the Magnetes. At this stone men marvel; indeed, it often makes a chain of rings all hanging to itself. For sometimes you may see five or more in a hanging chain, and swaying in the light breezes, when one hangs on to the other, clinging to it beneath, and each from the next comes to feel the binding force of the stone: in such penetrating fashion does its force prevail.
Much must be premised.In things of this kind much must be made certain before you can give account of the thing itself, and you must approach by a circuit exceeding long: therefore all the more I ask for attentive ears and mind.
(a) From all things bodies are always streaming off, which arouse our senses.First of all from all things, whatsoever we can see, it must needs be that there stream off, shot out and scattered abroad, bodies such as to strike the eyes and awake our vision. And from certain things scents stream off unceasingly; even as cold streams from rivers, heat from the sun, spray from the waves of the sea, which gnaws away the walls by the seashore. Nor do diverse sounds cease to ooze through the air. Again, moisture of a salt savour often comes into our mouth, when we walk by the sea, and on the other hand, when we behold wormwood being diluted and mixed, a bitter taste touches it. So surely from all things each several thing is carried off in a stream, and is sent abroad to every quarter on all sides, nor is any delay or respite granted in this flux, since we perceive unceasingly, and we are suffered always to descry and smell all things, and to hear them sound.
(b) The bodies of all things are porous;Now I will tell over again of how rarefied a body all things are; which is clearly shown in the beginning of my poem too.
For verily, although it is of great matter to learn this for many things, it is above all necessary for this very thing, about which I am essaying to discourse, to make it sure that there is nothing perceptible except body mingled with void.e. g. rocks, First of all it comes to pass that in caves the upper rocks sweat with moisture and drip with trickling drops.the human body. Likewise sweat oozes out from all our body, the beard grows and hairs over all our limbs and members, food is spread abroad into all the veins, yea, it increases and nourishes even the extreme parts of the body, and the tiny nails.metals, We feel cold likewise pass through bronze and warm heat, we feel it likewise pass through gold and through silver, when we hold full cups in our hands.walls, Again voices fly through stone partitions in houses, smell penetrates and cold and the heat of fire, which is wont to pierce too through the strength of iron. Again, where the breastplate of the sky
closes in the world all around
(c) These effluences affect different things differently: e. g. sunlight may melt or harden.There is this besides, that not all bodies, which are thrown off severally from things, are endowed with the same effect of sense, nor suited in the same way to all things. First of all the sun bakes the ground and parches it, but ice it thaws and causes the snows piled high on the high mountains to melt beneath its rays. Again, wax becomes liquid when placed in the sun’s heat. Fire likewise makes bronze liquid and fuses gold, but skins and flesh it shrivels and draws all together. Moreover, the moisture of water hardens iron fresh from the fire, but skins and flesh it softens, when hardened in the heat. The wild olive as much delights the bearded she-goats,The wild olive is good to goats, loathsome to us. Pigs hate marjoram, and we loathe mud. as though it breathed out a flavour steeped in ambrosia and real nectar; and yet for a man there is no leafy plant more bitter than this for food. Again, the pig shuns marjoram, and fears every kind of ointment; for to bristling pigs it is deadly poison, though to us it sometimes seems almost to give new life. But on the other hand, though to us mud is the foulest filth, this very thing is seen to be pleasant to pigs, so that they wallow all over in it and never have enough.
(d) The pores and passages in things differ, and let different things pass through them.This too remains, which it is clear should be said, before I start to speak of the thing itself. Since many pores are assigned to diverse things, they must needs be endowed with a nature differing from one another, and have each their own nature and passages. For verily there are diverse senses in living creatures, each of which in its own way takes in its own object within itself. For we see that sounds pass into one place and the taste from savours into another, and to another the scent of smells. Moreover, one thing is seen to pierce through rocks, another through wood, and another to pass through gold, and yet another to make its way out from silver and glass. For through the one vision is seen to stream, though the other heat to travel, and one thing is seen to force its way along the same path quicker than others. We may know that the nature of the passages causes this to come to pass, since it varies in many ways, as we have shown a little before on account of the unlike nature and texture of things.
We can now turn to the magnet.Wherefore, when all these things have been surely established and settled for us, laid down in advance and ready for use, for what remains, from them we shall easily give account, and the whole cause will be laid bare, which attracts the force of iron.It sends off particles which beat aside the air in front and make a vacuum; into this the atoms of the iron rush, and because they are very closely linked together, they draw the whole ring with them. First of all it must needs be n that there stream off this stone very many seeds or an effluence, which, with its blows, parts asunder all the air which has its place between the stone and the iron. When this space is emptied and much room in the middle becomes void, straightway first-beginnings of the iron start forward and fall into the void, all joined together; it comes to pass that the ring itself follows and advances in this way, with its whole body. Nor is anything so closely interlaced in its first particles, all clinging linked together, as the nature of strong iron and its cold roughness. Therefore it is the less strange, since it is led on by its particles, that it is impossible for many bodies, springing together from the iron, to pass into the void, but that the ring itself follows; and this it does, and follows on, until it has now reached the very stone and clung to it with hidden fastenings. This same thing takes place in every direction; 1 This may happen in any direction. on whichever side room becomes void, whether athwart or above, the neighbouring bodies are carried at once into the void. For indeed they are set in motion by blows from the other side, nor can they themselves of their own accord rise upwards into the air.Further, the air behind the ring pushes it towards the vacuum, where there is no air to beat it back. To this there is added, that it may the more be able to come to pass, this further thing as an aid, yea, the motion is helped, because, as soon as the air in front of the ring is made rarer, and the place becomes more empty and void, it straightway comes to pass that all the air which has its place behind, drives, as it were, and pushes the ring forward. For the air which is set all around is for ever buffeting things; but it comes to pass that at times like this it pushes the iron forward, because on one side there is empty space, which receives the ring into itself. This air, of which I am telling you, finds its way in subtly through the countless pores of the iron right to its tiny parts, and thrusts and drives it on, as wind drives ship and sails.The air inside the iron also pushes in the same direction. Again, all things must have air in their body seeing that they are of rare body, and the air is placed round and set close against all things. This air then, which is hidden away deep within the iron, is ever tossed about with restless motion, and therefore without doubt it buffets the ring and stirs it within; the ring, we may be sure, is carried towards the same side to which it has once moved headlong, struggling hard towards the empty spot.
When brass is interposed, the magnet repels iron, because the effluence from the brass has already filled up the pores in the iron.It comes to pass, too, that the nature of iron retreats from this stone at times, and is wont to flee and follow turn by turn. Further, I have seen Samothracian iron rings even leap up, and at the same time iron filings move in a frenzy inside brass bowls, when this Magnesian stone was placed beneath: so eagerly is the iron seen to desire to flee from the stone. When the brass is placed between, so great a disturbance is brought about because, we may be sure, when the effluence of the brass has seized before-hand and occupied the open passages in the iron, afterwards comes the effluence of the stone, and finds all full in the iron, nor has it a path by which it may stream through as before. And so it is constrained to dash against it and beat with its wave upon the iron texture; and in this way it repels it from itself, and through the brass drives away that which without it it often sucks in.
The magnet cannot move other things because they are either too heavy or too rare in texture.Herein refrain from wondering that the effluence from this stone has not the power to drive other things in the same way. For in part they stand still by the force of their own weight, as for instance, gold; and partly, because they are of such rare body, that the effluence flies through untouched, they cannot be driven anywhere; among this kind is seen to be the substance of wood. The nature of iron then has its place between the two, and when it has taken in certain tiny bodies of brass, then it comes to pass that the Magnesian stones drive it on with their stream.
There are other cases of things with a peculiar affinity and binding power: stones and mortar, wood and glue, wine and water, dye and wool,And yet these powers are not so alien to other things that I have only a scanty store of things of this kind, of which I can tell—things fitted just for each other and for naught besides. First you see that stones are stuck together only by mortar. Wood is united only by bulls’ glue, so that the veins of boards more often gape than the bindings of the glue will loosen their hold. The juice born of the grape is willing to mingle with streams of water, though heavy pitch and light olive-oil refuse. And the purple tint of the shellfish is united only with the body of wool, yet so that it cannot be separated at all, no, not if you were to be at pains to restore it with Neptune’s wave, no, nor if the whole sea should strive to wash it out with all its waves. Again, is not there one thing only that binds gold to gold? is it not true that brass is joined to brass only by white lead?brass and white lead. How many other cases might we find! What then? You have no need at all of long rambling roads, nor is it fitting that I should spend so much pains on this, but ’tis best shortly in a few words to include many cases.Whenever shapes fit mutually, a strong joining results. Those things, whose textures fall so aptly one upon the other that hollows fit solids, each in the one and the other, make the best joining. Sometimes, too, they may be held linked with one another, as it were, fastened by rings and hooks; as is seen to be more the case with this stone and the iron.
- Plague and disease.Now what is the law of plagues, and from what cause on a sudden the force of disease can arise and gather deadly destruction for the race of men and the herds of cattle, I will unfold. First I have shown before that there are seeds of many things which are helpful to our life,When the seeds of harmful things gather in the sky, they pollute it. They may come from outside the world or from the earth. and on the other hand it must needs be that many fly about which cause disease and death. And when by chance they have happened to gather and distemper the sky, then the air becomes full of disease. And all that force of disease and pestilence either comes from without the world through the sky above, as do clouds and mists, or else often it gathers and rises up from the earth itself, when, full of moisture, it has contracted foulness, smitten by unseasonable rains or suns.So travellers are affected by a strange climate, Do you not see, too, that those who journey far from their home and country are assailed by the strangeness of the climate and the water, just because things are far different? For what a difference may we suppose there is between the climate the Britons know and that which is in Egypt, where the axis of the world slants crippled; n what difference between the climate in Pontus and at Gades, and so right on to the black races of men with their sunburnt colour?and differences of climate cause differences of appearance in races, and produce special diseases. And as we see these four climates at the four winds and quarters of the sky thus diverse one from the other, so the colour and face of the men are seen to vary greatly, and diseases too to attack the diverse races each after their kind. There is the elephant disease, which arises along the streams of the Nile in mid Egypt, and in no other place. In Attica the feet are assailed, and the eyes in the Achaean country. And so each place is harmful to different parts and limbs: the varying air is the cause. Wherefore, when an atmosphere,If then a noxious atmosphere moves and comes to us. which chances to be noxious to us, sets itself in motion, and harmful air begins to creep forward, just as cloud and mist crawls on little by little and distempers all, wherever it advances, and brings about change, it comes to pass also, that when at last it comes to our sky, it corrupts it and makes it like itself, and noxious to us.pestilence results for man and beast. And so this strange destruction and pestilence suddenly falls upon the waters or settles even on the crops or on other food of men or fodder of the flocks; or else this force remains poised in the air itself, and, when we draw in these mingled airs as we breathe, it must needs be that we suck in these plagues with them into our body. In like manner the pestilence falls too often on the cattle, and sickness also on the lazy bleating sheep. Nor does it matter whether we pass into spots hostile to us and change the vesture of the sky, or whether nature attacking us brings a corrupt sky 1 upon us, or something which we are not accustomed to feel, which can assail us by its first coming.