Aristotle · a new plain-English translation from the original language
1| BOOK 23. PROBLEMS CONCERNING SALT WATER AND THE SEA. Why does the wave not break into foam on the deep open seas, but on shallow and short waters? Is it because a small body of water in motion is divided by the wind more than a large one?
2| Why do the waves sometimes travel ahead of the winds? Is it because, at the point where the wind begins, the sea, having first been pushed, always does the same thing to the water next to it? Hence, since the sea is continuous, it is as though a single continuous blow occurs for all of it at once. And this happens in one time, so that it turns out the first part and the last part are moved at the same moment. Air does not undergo this, because it is not a single continuous body, in that it receives many collisions from every direction, which often hinder the first and most vigorous motion; and they do not produce this effect in the sea, because the sea is heavier and harder to move than air. Why do ships seem to be more heavily laden in the harbor than on the open sea, and why do they run faster from the open sea toward land than from land toward the open sea? Is it because the greater volume of water pushes back more, arising from the smaller volume, while in the smaller volume the ship has sunk down more because it more easily overcomes it? For the water pushes upward from below. In the harbor, then, the sea is shallow, but on the open sea it is deep. So the ship will seem to be carrying more in the harbor, and it will move with more difficulty because it has sunk down more and the water pushes back less. On the open sea the opposites of these hold.
3| Why is it that, when something is thrown into a wave-tossed sea, such as an anchor, a calm occurs? Is it because the sea comes to a stop around the moving object, and along with it air is carried down together, which, being carried straight down and drawn in there, drags along with it the thing that from the side was moving the sea? Now the surge of the sea does not occur from above downward but on the surface; and when this ceases, a calm occurs. Further, the sea, coming together into the space parted by the moving object, produces a whirl. And the whirl is carried in a circle. Since a straight line touches a circle at a point, and the waves are carried along a slanting straight line, it would follow that they touch the outermost part of the whirl at a point, both for the reasons stated and because of the whirl's motion, or else, as it approaches, they are pushed away by it. And since the place at the whirl itself is without waves, it turns out that a calm occurs at its breaking-point, because the air, having gone down together with the object carried down, is carried back up and, pushing the sea upward, makes it bubble up, as it were; for a bubble is of liquid pushed up from below by air. And every bubble is smooth and calm. There are signs of what has been said: for the sea at the place where the object was carried down becomes elevated above the sea around it a little later.
4| Why is it that sometimes ships running on the sea in calm weather are swallowed up and disappear, so that not even wreckage floats back up? Is it because, when a cavernous place in the earth beneath the sea breaks open, the sea follows down into it together with the motion of the wind, both into the sea and inward? And likewise, being carried in every direction, it is carried in a circle downward. And this is a whirlpool. What happens in the strait around Messina happens for this reason, on account of the current (for the whirlpools arise from this), and it is swallowed into the depths both for these reasons, and because the sea there is deep and the land is hollowed out with caverns far underneath. The whirlpools, then, forcing their way, carry things into these caverns; hence the wreckage does not float back up there. And the current arises whenever, the earlier wind having stopped, a contrary wind blows against the sea which is still flowing in the direction of the earlier wind, especially when a south wind blows against it. For the currents, blowing against each other, are squeezed out sideways just as in rivers, and whirlpools arise. And the origin of the motion is carried spiraling, being strong from above. Since, then, it cannot rush off to the side (for the currents push against each other), it is necessarily pushed into the depths, so that whatever is caught by the whirlpool is necessarily carried down together with it. This is why ships are made to point upward as they go down; for indeed a case is recorded of a ship once being swallowed standing upright.
5| Why is the sea whiter in the Black Sea than in the Aegean? Is it because of the reflection of sight that occurs from the sea into the air? For the air around the Black Sea is thick and white, so that the surface of the sea also appears that way, while the air over the Aegean is deep blue, because it is clear far into the distance, so that the sea too, shining back, appears that way. Or is it because all lakes are whiter than the sea? And the Black Sea is lake-like because many rivers flow into it. Lakes are whiter than both the sea and rivers: painters, at any rate, paint rivers pale yellow but the sea deep blue. Or is it because sight passes quickly through fresh water and is not reflected toward the air, whereas from the sea it is not so? For sight is not reflected upward, because the water is not smooth, but going downward it grows weary; that is why the sea appears dark. But in lake-like places, since the fresh water lies on the surface and the salt water below, sight does not pass through but is reflected back toward the light; that is why the surface of such water appears white.
6| Why is the sea less cold than fresh water, and salt water less cold than sweet water? Is it because the sea is denser and more of a body? Such things are cooled less, just as they are heated more, since through their density they are more able to conserve heat. Or is it because the sea is oilier? That is also why it does not extinguish flame; and likewise with other things. And what is oilier is hotter. Or is it because the sea contains much earth, so that it is drier? And what is drier is hotter. Why is the sea, though thicker, easier to see through than fresh water? For fresh water is finer than salt water. Or is fineness not the cause, but rather that the straight channels in it are most numerous and largest? Fresh water is dense on account of the fineness of its parts, while salt water has large gaps in it. Or is it because the sea is purer? For it contains no earth, since the sand, being heavy, settles to the bottom; but fresh waters are earthy, and being carried along in between, quickly become muddied. Why is the sea easier to see through in northerly weather than in southerly? Or is it because the sea has color in calm weather? For an oily element is present in the salty liquid; and there is a sign of this — oil is extracted from it in hot weather. So when the weather is fair and the sea is warmer on account of its lightness, this oily substance floats up and blooms on the surface. In northerly weather it does so less, because of the cold. Now water is easier to see through than oil, for oil has color, whereas water, being colorless and letting things show through it, makes the reflected image clearer.
7| Why do people who have bathed in the sea dry faster, although sea water is heavier than fresh water? Is it because the sea is thicker and earthy? Having little moisture in it, then, it dries faster. Why are waves signs of wind? Is it because they are signs of wind that is going to come? For wind is a compacting of air. Or do they arise because something is always being pushed forward? What does the pushing is wind that is not yet continuous but only beginning. The first wave, as it were, dies away beforehand, but another pushes this one forward and brings on another density and then itself dies away. So it is clear that, once what is pushed forward is already present, what causes the motion will also come; for this is what a wind does when it is beginning. Why does the wave fall before the wind? Is it because the blowing wind and the sea's waving do not stop at the same time, but the sea stops later, and it is possible for the wind that caused the motion to have died away before it becomes perceptible? So the wave is not really prior to the wind, but one goes unnoticed and the other does not. Or is it not the case that winds blow everywhere at once, but rather blow first from where their source is? At the same time it blows there, it also moves the nearby sea, and this in turn moves the sea next to it; and in this way it would be possible for the wave to fall before the wind is perceived. For the motion that is faster than the wind or the sea is caused by the sea, not by the wind.
8| Why are people better able to swim in the sea than in rivers? Is it because a swimmer always swims by bracing himself against the water, and we are able to brace ourselves better against something more bodily, and sea water is more bodily than river water? For it is thicker and more able to push back against us. Why can people stay afloat for a longer time in the sea than in a river? Is it because river water is fine? Being finer, it seeps in more and so chokes a person more. Why does the sea burn, while fresh water does not? Or does fresh water also burn, but the sea extinguishes fire less because it is oilier? A sign that it is oilier: oil is extracted from salt. Or is it also that the channels of sea water are less able to fit close around the fire because they are thicker, and all the more so, since salt is present in it as well? Just as the dry is less able to extinguish than the moist, so too the dry is proportionally more able to burn, and one thing more than another according to how much nearer it is to the hot; and the sea is drier than fresh water, and both these properties belong to it more.
9| Why does no cold breath come off the sea at dawn, but it does come off rivers? Is it because the sea lies in open spaces, while rivers lie in narrow ones? So the breeze from the sea is scattered over a large space, so that it is weak, while the breeze from rivers travels in a mass and is stronger, and so it reasonably appears colder. Or is this not the cause, but rather that rivers are cold while the sea is neither hot nor cold? A breeze, an exhalation, arises when liquids are being heated or cooled; for whichever of these it undergoes, it turns into vapor, and as the water turns into vapor, the air that forms travels, and this is the breeze. So what comes off cold things is reasonably cold, while what breathes off things that are very hot cools as it goes and becomes cold. Now one would find that rivers are all cold, while the sea is neither very cold nor very hot; so what breathes off it is not cold, because the sea is not cold, nor does it cool quickly, because the sea is not very hot. Why do the waves settle more slowly in larger open seas than in shallow ones? Is it because everything that has undergone much motion settles more slowly than what has undergone little? And in large open seas the ebb tide is greater than in shallow ones. So there is nothing unreasonable in the greater motion settling more slowly.
10| Why is salt water, when cold, not drinkable, but becomes more drinkable when heated, and also when it is hot and then cooled again? Is it because it is the nature of a thing to change from one contrary into the other? Fresh water is the opposite of salt water; and when it is heated, the salt water is boiled off, while when it is cooled, the salt settles out. Why are the waters near the sea generally sweet rather than salty? Is it because they become sweeter by being filtered, and water nearer the sea is filtered more? Why is salt water not free-flowing? Is it because what is heavy tends to remain still, and salt water is heavy? That is also why only hot salt waters flow freely — for they have a lightness in them that overcomes the heaviness due to their saltiness, since what is hot is lighter. Further, free-flowing waters are filtered through the earth, and as they are continually being filtered, what is thickest and heaviest settles out the most, while what is light and pure is separated out; for what is salty is heavy, and what is sweet is light. That is why free-flowing waters are sweet. And the same cause explains why salt water, when set in motion and changed about, becomes sweeter: it becomes lighter and weaker through the motion.
11| Why is it that in Libya, if someone digs near the sea, the water is at first drinkable, but then quickly becomes salty, while in other places this happens less? Is it because the water that first exists in the place, and has been concocted by the earth, is fresh, but when time passes, the sea, seeping in gradually, makes it saltier, since the fresh water is no longer being renewed? Whereas in other places either there is no such seepage, or there is a great deal of water, because the place does not dry out. Why does salt water melt salt faster than fresh water does? Is it because melting is a matter of being divided by moisture or heat entering in, so as to become liquid? Now things do not melt either what is altogether unable to enter, or what enters in such a way as not to make contact. And what passes through easily melts only with difficulty, whereas what presses in forcibly divides most quickly. Now the particles that are too large in bulk do not enter at all, for they exceed the size of the pores; but the smaller particles pass through without touching. Fresh water is fine-grained, while salt water is coarser, so that fresh water, passing through easily because of its fineness, melts salt only with difficulty, while salt water does enter, but divides less because its particles are larger — yet it presses in more forcibly, and so acts more quickly.
12| Why does water appear less white when it is in motion, as also with a ripple? This is why Homer, of the wind beginning, says the sea grows dark beneath it. Is it for two reasons: because, when sight is close by, sight passes through more readily when the water is at rest, but when it is in motion, sight does not travel straight through — and what is transparent appears white? For that through which sight does not pass, he says, is dark. This is also why the air appears dark from far off, but white close up, and of the sea, the part close by is white, but the part far off is deep blue and dark. And from far off, since sight is in a way in motion, and because sight is reflected back all at once, if it is at rest facing the light it can do so, but when it is in motion it cannot. Why is it that on the deep seas the wave does not break into foam, but on shallow ones it does? Is it because the small quantity of water carried along is divided by the air more than a large quantity is? This is why it shatters more when it strikes. So in deep water a great quantity is in motion, but in shallow water only a little. Why do places toward the south have saltier waters? Is it because the sea, being pushed by the south wind, is driven under the land and mixed in?
13| Why does the salty part of water float more on top of sweet wine than on dry wine? Is it because the sweet wine has more earth in it, as does a raisin? Or is it because sweet wine is heavier and thicker, so that it mixes less, and not mixing, the salt water sits on top? Why does it sit on top at all, being earthy? For its natural motion is downward. Is it because the sweet wine has more earth in it? Or is it on account of heat, as with salt? For it is like an efflorescence. Or is there another cause? For if this is not the reason, and it also happens more with sweet wine, that is not unreasonable, since sweet wine is hottest. Why do the waves sometimes arrive before the winds? Is it because they also end later? For the first breath of wind, as it were, dissolves itself into the wave it has pushed forward; and what arrives is not the very first thing pushed, but the pushing is always passed on to what is next in line.
14| Why do shores with more waves often become as firm and hard as though they had been paved? And a shore exposed to waves is firm, while one further off is loose. Is it because small sand is not thrown far by the wave, but larger grains are thrown farther? Just as with throwing by hand, it is not the smallest thing that can be thrown farthest. Then, as many grains are churned together, the smallest ones falling in pack it tight. And the wave's motion, as it subsides, levels the ground, but no longer stirs it up. So then, because the smallest grains cannot leap far, the shore near the water is composed of very fine particles; and because the motion happens repeatedly, it becomes continuous as the sand keeps falling, until it fits closely together; and because of the last wave it is leveled flat, and the gently moving moisture cements it together. But the sand far off, being dry, stays apart, and is made of larger pebbles, and is not leveled.
15| Why is the upper part of the sea saltier and warmer than the water in the depths? And likewise in freshwater wells, the water at the surface is saltier than the water at depth — yet one would expect the opposite, since salt water is heavier. Is it because the sun and the air are always drawing up the lightest part from moisture? And the fresher part is always lighter, and is drawn off more from the places nearer the surface. So it is necessary that both from the sea's surface and from fresh water, what remains behind, from which the light part has been drawn up, is saltier than what has none, or less, of the sweet part drawn from it. This is also why the upper waters are warmer, for salt water is warmer than fresh. This is also why some of the followers of Heraclitus say that from fresh water, when it dries and solidifies, stones and earth are formed, while from the sea the sun draws up vapor. Why is the sea sweeter near the land? Is it because it is more in motion there? And salt water, when in motion, becomes sweeter. Or is it because the water is also saltier in the depths, and the parts near the land are less deep? This is also why waters near deep drop-offs are salty and not sweet in the same way. The cause of this is that salt water, being heavy, tends more to sink into the depths.
16| Why does the sea alone among waters burn, while fresh and river waters do not? Is it because it contains much earth? The salt shows this. Or is it because it is oily? The oil that settles out in salt shows this. Why does sand not form in lakes, or form less than in the sea and rivers? Is it because rocks form in the sea, and the ground there is most burned out by the sun? And sand is rock rubbed down into small and very fine particles. It is rubbed down by the battering of the waves. But in lakes clean rocks do not form in the same way, nor are they broken up in the same way, because waves do not occur there in the same way. In rivers it happens more, because rivers carry earth down and break up rocks by battering them.
17| Why is it that, when a lake either subsides or becomes dry, the grain in the plain is more scorched by frost? Is it because the moisture in the lake, evaporating, warms the air with its vapor, so that it makes the frosts fewer and weaker than in hollow and marshy places nearby? Or is it that, as is said, the cold begins from the earth and creeps in unnoticed — so that, when the lake is dry, the cold, falling over a greater area, freezes and scorches more? And in such regions the cold arises from below, as indeed it seems to. And yet the earth is warm in winter; but because it is moist, the warmth at the surface of the earth is chilled. For the moisture is neither so deep that it fails to be cooled, on account of the heat present in moist things, nor so slight that it has no effect, on account of the earth being soaked through. So it is, in a sense, on account of its being chilled, that it happens that one walks and dwells as if on ice. Why is the sea salty and bitter? Is it because there are several flavors present in the sea? For the salty and the bitter appear together.
18| Why do shells and stones in the sea become round? Is it because, being worn away all around in the same way, their extremities come into a round shape? For the extremity of a round thing is uniform, and the sea, moving on every side alike, wears them away uniformly. Why is it that in some places, if one digs near the sea, the water is at first drinkable, but then becomes salty? Is it because it is water of the sea itself, filtering under the earth? It is reasonable, then, that the first water is sweet; for the sweet is lighter than the salty, and the sea has some sweetness in it, which, when mixed with the earth, rises more to the surface. The salty part, on the other hand, is carried down because of its weight and because it is cutting. Whether, then, it is in this way, or whether sweet water flows to the sea through channels from the mainland, it is reasonable that it should be on the surface of the sea, where it mixes with it. But once the passages are opened up, later on, because of its abundance, the salty water prevails and makes everything of that kind. For it happens that, when the upper passages are blocked, the water flowing in seeks another route, but once they are opened, all of it is carried there, just as with the veins of the body.
19| Why is the sea, although heavier than fresh water, more transparent? Is it because it is oilier? For oil poured on top makes water more transparent, and since the sea has fat in it, it is reasonable that it should be more transparent. Or is it not the case that everything lighter is also more transparent? For oil itself is lighter than water, but not more transparent. Or is it not actually more transparent, but only appears so? For fresh water comes from the earth or from streams, and the spring sends up earth along with the water, so that, the streams not being pure, they carry down earth and mud with them. This, then, is the cause of its being less transparent. Why do those who swim in the sea become loose-bodied? For if it is because they exert themselves, then those who run on the wheel also exert themselves strenuously and are not made slack. Is it, rather, that not every exertion produces slackening, but only that which does not produce a wasting away? Time spent in the sea, and in general, seems to make people more prone to hunger and loose-bodied; for the vapor rising from it is hot and dry.
20| Why does every lake, if it is fresh, both wash and cleanse clothes? For the sweet washes, while the bitter cleanses, and it is not possible to have both at once. Or is it not by being bitter that anything cleanses, but rather stickiness that is what cleanses? That is why the extremities of animals and whatever is mucous are of this kind, so that even among bitter things, those that share in this stickiness cleanse. Now in this particular lake it happens that, of its natron-like power, the bitter part has been burned away, while the fatty and sticky part remains. By this, then, it cleanses, and it washes by means of its fresh water. Why does the calm part of the sea appear white, while the surging part appears black? Is it because what is less clearly seen appears darker? And what is in motion is seen less clearly than what is at rest. Or is it because what lets light show through appears white, and what does not appears black? And what is in motion lets light show through less.