by Aristotle
6 · Why is the water whiter in the Black Sea than in the Aegean? Is it owing to the refraction of the vision from the sea into the air? For in the region of the [25] Black Sea the air is thick and white, so that the surface of the sea appears to be similar, whereas in the Aegean it is blue, because it is clear to a great distance, and so the sea too reflecting the air appears to be similar. Or is it because all lakes are whiter than the sea, and the Black Sea has the character of a lake because many [30] rivers flow into it? Now lakes are whiter than the sea, and than rivers; at any rate, painters picture rivers as pale yellow and the sea as blue. Or is it because the sight cannot penetrate quickly through fresh water and is refracted into the air,2 but is not refracted upwards from the sea, because the water is not smooth, but the sight [35] tires of trying to penetrate into the depths, and so the sea appears black? But in seas of a lake-like character, since the fresh water is on the surface and the salt water below, the sight does not penetrate, but is refracted towards the daylight; and so the surface of the sea appears white.
7 · Why is the sea less cold than fresh water, and salt water in general than [932b1] sweet? Is it because the sea is denser and has more body? Now such things are less susceptible to cold, just as they are more easily heated; for owing to their density they are better able to retain heat. Or is it because the sea is of a more fatty composition and so does not extinguish fire? (And similarly in other cases.) And the [5] more fatty anything is the hotter it is. Or is it because it contains much earth and is therefore drier, and the drier a thing is the hotter it is?
8 · Why is the sea more transparent than fresh water, although it is thicker? For fresh water is rarer than salt. Or is the cause not its rarity but the fact that in it there are direct interstices which are very numerous and wide? Fresh water, [10] therefore, has density owing to the small particles of which it is composed, whereas salt water contains great voids. Or is it because the sea is purer? For there is no earth in it, but the sand, which is heavy, is precipitated; but fresh water is earthy, and the earth floating in its midst is easily stirred into mud. [15]
9 · Why is the sea more transparent when the wind is in the north than when it is in the south? Is it because the sea has colour when it is calm? For there is something fatty in the juice of salt water, as is shown by the fact that in hot weather an oily substance is excreted from the sea. When, therefore, the sea is calm and [20] warmer, juice of this kind forms on the surface of the sea owing to its lightness. This is less likely to happen when the wind is in the north, owing to the cold. Now water is more transparent than oil; for oil has colour, but water, presenting itself without colour to the vision, gives a clearer image.
10 · Why does one dry more quickly after washing in the sea, although sea [25] water is heavier than fresh? Is it because the sea is thicker and earthy? Since, therefore, it has little moisture in it, it dries more quickly.
11 · Why are the waves windy? Is it because they are a sign of wind in the future? For wind is a massing together of air, which3 occurs because the air is [30] continually thrust forward. But the wind begins to thrust the air forward when it is not yet blowing continuously but only just beginning. The first breath of wind then as it were dies down before having any effect, but it thrusts forward another breath and drives on another mass of air and then dies away. It is clear therefore, when the wave which is thrust forward is already present, that that which sets it in motion [35] will also come; for it causes this effect when it first begins to blow.
12 · Why do the waves break forth before the wind? Is it because the wind does not cease to blow4 and the sea to be rough at the same time, but the sea ceases later? For5 it is possible that the wind which set the wave in motion perishes before [933a1] it becomes perceptible; and so the wave is not prior to the wind, but the former is noticeable, while the latter is not. Or do the winds not blow everywhere at the same time, but at first only in the quarter from which they arise? Now as soon as they begin to blow, they set in motion the sea which is near them, and this sets in motion [5] the adjoining sea; and thus it would be possible for the wave to break forth before the wind reaches it. For the movement is due to the sea and not to wind, being a movement of the sea which travels more quickly than that of the air.6
13 · Why is it easier to swim in the sea than in a river? Is it because the [10] swimmer always leans on the water as he swims, and we receive more support from that which is of a more corporeal nature, and sea water is more corporeal than river water, for it is thicker and able to offer more resistance to pressure?
14 · Why can one remain longer in the sea than in a river? Is it because river [15] water is rare and therefore penetrates more into the body and chokes one?
15 · Why is the sea combustible, while water is not? Or does water also burn, while the reason why the sea has less power to extinguish fire is because it is of a more fatty composition? (And that it is so indicated by the fact that an oil is given [20] off from sea water.) Or are the interstices less able to adapt themselves to fire because they are too wide, and all the more so owing to the presence also of salt? As, therefore, that which is dry has less power to quench than that which is moist, so that which is drier is proportionately more capable of being burnt, one thing being [25] more so than another, since the drier a thing is the more closely allied is it to heat;7 and the sea possesses both these qualities to a greater extent.
16 · Why is it that the wind blows cold in early morning from rivers, but not from the sea? Is it because the sea extends over open spaces, but rivers are in narrow [30] places? The breeze, therefore, from the sea is dispersed over a wide area and is consequently weak; whereas the breeze from a river is carried along in a mass and is stronger and therefore naturally seems colder. Or is the reason other than this, [35] namely, that the rivers are cold, but the sea is neither hot nor cold? Now a breeze or an exhalation is due to the heating or cooling of liquids; for whichever of these two processes they undergo, evaporation takes place, and, when water evaporates, the resultant air is set in motion, and this is a breeze. That which is produced from cold liquids naturally blows cold, while that which blows from very hot liquids cools and becomes cold. One would, therefore, find that all the rivers are cold, but that the sea [933b1] is neither very hot nor very cold. That which blows from it, therefore, is not cold, because it is not itself cold, nor does it cool quickly, because it is not very hot.
[5] 17 · Why do waves calm down more slowly in the wider open sea than in shallow waters? Is it because everything calms down more slowly after much motion than after little? Now in the wide open sea the ebb and flow is greater than in shallow waters; there is, therefore, nothing strange if that which is greater is more slow in calming down. [10]
18 · Why is it that salt water when it is cold is not fresh, but becomes more fresh when it is heated, and when it is heated and then cooled? Is it because a thing naturally changes from one opposite into the other? Now fresh water is the opposite of salt water; and, when salt water is heated, the salt is boiled out, and, when it [15] cools, is precipitated.
19 · Why is it that waters near the sea are usually sweet and not salty? Is it because water which is strained becomes more fresh, and the nearer water is to the sea the more it is strained? [20]
20 · Why does salt water not flow readily? Is it because that which is heavy is stationary, and salt water is heavy? Hence only warm salt waters flow readily, for they have lightness in them which prevails over the heaviness which is in their saltness; for that which is hot is lighter. Furthermore, water which flows readily is [25] strained through the earth; and if water is strained, the thickest and heaviest part of it is always carried to the bottom, while the light and clean element becomes separated. For salt water is heavy and sweet water is light. And so flowing water is sweet. It is for the same reason that salt water, when it is set in motion and [30] undergoes change, becomes sweeter; for it becomes lighter and weaker owing to the motion.
21 · Why is it that in Libya,
if one digs a hole near the sea, the water that first comes is fresh, but afterwards quickly becomes salty, but this happens less elsewhere? Is it because the water which comes first is the water which was already [35] there and has been concocted by the earth, but after a time the sea also is strained through and, because it is new, makes the water more salty? Elsewhere, however, there is either no water or abundant water, because the ground is not dried up.
22 · Why does salt water melt salt more quickly than fresh water? Is it [934a1] because the process of melting anything is its dissolution by moisture or heat penetrating into it so that it becomes liquid? Now those things do not cause melting which either cannot penetrate at all or penetrate in such a way as not to touch the substance. Those things which pass through easily scarcely cause any melting, but [5] those which enter in with violence dissolve substances very quickly. Now those liquids which are composed of very large particles do not penetrate, for they are too large for the pores; while those which are composed of small particles pass through without touching. Now fresh water is rare, while salt water is thicker; and so the former, passing through easily owing to its rarity, scarcely causes any melting, [10] whereas the latter penetrates, but percolates through8 to a less extent, because it is composed of larger particles, and forces its way in more quickly.
23 · Why does water appear less white when it is in motion, for instance when there is a ripple? Whence Homer says that, when the wind begins to blow,
[15] the sea grows blacker beneath it.9
Are there two reasons? Firstly, because, when the sight is near to it, it can penetrate farther through the water when it is still, but when it is in motion the sight cannot pass directly through it. (And that which is transparent appears white, for that through which the sight cannot pass is what Homer calls black; therefore the air appears black from a distance but white near at hand, and the part of the sea which [20] is near is white, while that which is distant is blue or black.) And, secondly, because, when the sight is at a distance and is subject in any way to disturbance, it is refracted back in a mass towards the light, if the water is still, but cannot be refracted when it is in motion.
[25] 24 · Why is it that the waves do not ripple in the deep, open sea, but only on small expanses? Is it because a small amount of water, as it is carried along, is more divided by the air than a large amount? Hence it beats more and is broken up. Now in deep water the quantity which is set in motion is great, but in shallow water it is small.
[30] 25 · Why are the waters saltier in regions facing the south wind? Do they become mixed because the sea is driven under the earth by the south wind?
26 · Why does the salty element in water come to the surface more in sweet than in dry wine? Is it because sweet wine, like raisin wine, has more earth in it? Or [35] is it because sweet wine is heavier and stickier and so mixes less, and, as it does not mix,10 the salty element comes to the surface?
27 · Why does the salty element, being earthy, float on the surface at all (for [934b1] its natural tendency is to sink)? Is it11 owing to its heat, as happens with salt (for it resembles an efflorescence)? Or is there some other reason? For if it is for no other reason,12 it is not unreasonable that it should be for this reason that it floats specially on the surface of sweet wine; for that is the hottest of wines.
28 · Why do the waves sometimes begin to move before the winds reach [5] them? Is it because they also cease to move later? For the first breath of wind as it were dies down before the wave which has been impelled by it into motion; and it is not the wave which is first set in motion that arrives, but there is a successive impetus given to the adjoining water.
29 · Why is it that the ground where the waves break more violently becomes solid, often to such an extent as to appear to have been artificially levelled, [10] and why is the ground where the waves break solid, whereas further from the sea it is loose? Is it because the fine sand is not cast up from a long way off by the waves, but rather the coarser sand, just as it is not possible to throw a very small object far with the hand? Then, many objects being mingled in confusion, the smallest particles fall together and form into a mass, and the motion of the wave, as it [15] recedes, levels them and no longer disturbs them. Since, then, the smallest particles cannot leap far, a mass is formed of very small objects; and since it is in frequent motion, it becomes continuous, the sand falling in amongst it until it unites it together; it is then levelled by the last waves, and the slight moisture causes it to [20] adhere together. But the ground farther from the sea, being dry, becomes disintegrated, and is formed of larger pebbles and is unlevelled.
30 · Why is it that the upper parts of the sea are saltier and hotter than the depths? So, too, in wells of fresh water the upper water is saltier than that at the bottom; yet salty water, being heavier, ought to stand at a lower level. Is it because [25] the sun and the air always attract the lightest part of liquid? Now the fresher is always lighter, and the sun can more easily attract things from the nearest parts. And so that which is left on the surface both of the sea and of fresh water is saltier [30] (since the sweet element has been extracted) than that from which little or nothing has been withdrawn. For this reason the upper part is also hotter; for salt water is hotter than fresh. Therefore some of the followers of Heraclitus declare that stones [35] and earth are formed from the drying and solidifying of fresh water and that the sun draws up vapours from the sea.
31 · Why are the waters of the sea sweeter which are nearer the land? Is it because they are more continuously in motion? Now salt water becomes sweeter through motion. Or is it because the water is saltier in its depths, and the part of the [935a1] sea near the land is less deep? Hence also water which shelves quickly is salty and less sweet. The reason for this is that the salty element being heavy is carried down more into deep water.
32 · Why is sea water the only kind of water that is combustible, whereas [5] fresh water and river water are not? Is it because it has much earth in it, as is proved by the presence of the salt in it? Or is it because it is of a fatty composition, as is proved by the oil which forms on the surface13 of salt water?
33 · Why does sand not form in lakes, or at any rate less than in the sea and in rivers? Is it because rocks form in the sea and the earth has been to a great extent [10] burnt out of them? Now sand is rock which has been broken up into small and minute particles, and it is broken up by the impetus of the waves. But in lakes pure rocks are not formed to the same extent, nor are they broken to the same extent, [15] because there are not waves to the same extent. But sand is formed more in rivers, because they carry down the earth and break up the rocks with their impetus.
34 · Why is it that, when a lake either falls or dries up, the corn in the adjoining plain is more likely to be frosted? Is it because the moisture in the lake [20] evaporates and warms the air with its vapour, and so makes the frosts slighter and weaker than in hollow and marshy districts? Or is it from the earth, as men say, that the cold begins and penetrates unnoticed? If then the lake becomes dry, owing to [25] the larger space of earth greater cold attacks the crops and freezes them and frosts them to a greater extent; and on such ground the cold comes from below, as indeed seems to be the case. And yet the earth is warm in winter; but the surface heat which is in the earth, owing to the fact that it is moist, becomes cooled, for the [30] moisture is neither so far in as not to be affected by cold, owing to the heat which is present in liquids, nor so slight as to have no force, since the earth is permeated with water. For instance, owing to its becoming cold, one walks and lives upon ice.
35 · Why is the sea salty and bitter? Is it because the juices in the sea are [35] numerous? For saltness and bitterness appear at the same time.
36 · Why do shells and stones which are in the sea become round? Is it because the breaking off of their extremities equally on every side causes them to [935b1] assume a round form? For the outer surface of this shape is the same on all sides, and the sea by moving objects in every
direction breaks off their extremities equally.
37 · Why is it that sometimes, if one digs a hole near the sea, the first water which enters is fresh but afterwards it becomes salty? Is it because the water comes [5] from the sea itself which is strained under the earth? The water which first comes is, therefore, naturally sweet; for sweet water is lighter than salt water, and the sea has some sweetness in it, which mingling with the earth tends to come to the surface. But the salt water, owing to its weight and to the fact that it has power to penetrate, is carried downwards. Whether this is so or whether the sweet water flows from the [10] mainland into the sea through the earth’s veins, it would naturally float on the surface of the sea which mingles with it; but, the passages being opened, the salt water, owing to its greater volume, subsequently prevails and makes the whole sea salty. For if the passages are blocked the result is that the inflowing salt water finds [15] another way higher up;14 but when they are opened, it is all carried there, just as happens in the veins in the body.