Lecture 5 — The saltiness of the sea according to the opinions, of others.

To return to the saltiness of the sea: those who create the sea once for all, or indeed generate it at all, cannot account for its saltiness. It makes no difference whether the sea is the residue of all the moisture that is about the earth and has been drawn up by the sun, or whether all the flavor existing in the whole mass of sweet water is due to the admixture of a certain kind of earth. Since the total volume of the sea is the same once the water that evaporated has returned, it follows that it must either have been salt at first too, or, if not at first, then not now either. If it was salt from the very beginning, then we want to know why that was so; and why, if salt water was drawn up then, that is not the case now.

Again, if it is maintained that an admixture of earth makes the sea salt (for they say that earth has many flavors and is washed down by the rivers and so makes the sea salt by its admixture), it is strange that rivers should not be salt too. How can the admixture of this earth have such a striking effect in a great quantity of water and not in each river singly? For the sea, differing in nothing from rivers but in being salt, is evidently simply the totality of river water, and the rivers are the vehicle in which that earth is carried to their common destination.

It is equally absurd to suppose that anything has been explained by calling the sea 'the sweat of the earth', like Empedicles. Metaphors are poetical and so that expression of his may satisfy the requirements of a poem, but as a scientific theory it is unsatisfactory. Even in the case of the body it is a question how the sweet liquid drunk becomes salt sweat whether it is merely by the departure of some element in it which is sweetest, or by the admixture of something, as when water is strained through ashes. Actually the saltiness seems to be due to the same cause as in the case of the residual liquid that gathers in the bladder. That, too, becomes bitter and salt though the liquid we drink and that contained in our food is sweet. If then the bitterness is due in these cases (as with the water strained through lye) to the presence of a certain sort of stuff that is carried along by the urine (as indeed we actually find a salt deposit settling in chamber-pots) and is secreted from the flesh in sweat (as if the departing moisture were washing the stuff out of the body), then no doubt the admixture of something earthy with the water is what makes the sea salt. Now in the body stuff of this kind, viz. the sediment of food, is due to failure to digest: but how there came to be any such thing in the earth requires explanation.

Besides, how can the drying and warming of the earth cause the secretion such a great quantity of water; especially as that must be a mere fragment of what is left in the earth?

Again, waiving the question of quantity, why does not the earth sweat now when it happens to be in process of drying? If it did so then, it ought to do so now. But it does not: on the contrary, when it is dry it graws moist, but when it is moist it does not secrete anything at all. How then was it possible for the earth at the beginning when it was moist to sweat as it grew dry? Indeed, the theory that maintains that most of the moisture departed and was drawn up by the sun and that what was left over is the sea is more reasonable; but for the earth to sweat when it is moist is impossible.

164. After determining about the nature of the sea and about its generation, the Philosopher now determines about its saltiness.

First, he inquires about it according to the opinions of others;

second, he presents his own opinion at **since all the attempts **(357b23).

With respect to the first he continues with the salt of the sea according to the three opinions of the natural philosophers presented in the beginning of this treatise on the sea.

165. He says therefore first (357a5) that those who declared that the sea was at one time generated, or posit its generation in any way, cannot assign a reason for its saltiness. For they say that in the beginning water surrounded the entire earth and that the sun raised aloft a great portion of the water, leaving a large area of the earth no longer covered with water, and that the residue, not yet dried up by the sun, became the sea. Now, if the cause of salt in the totality of the sea's water (which according to its nature ought to be sweet), came about because of earth's mixing with the water that remained, which was able to convert the sweet into so great saltiness, then, since, with the return in the form of rain of the evaporated water, there necessarily results an equal amount of water's being preserved on earth, as was said, it is necessary that even in the first place, before the sun began its drying process, that the sea be salty; or if it was not salty before, it will not be salty later, because all the evaporated water returns. Consequently, it cannot be said that mixing with earth makes the water salty because now it exists in a smaller amount, while it could not make the total amount salty—since the amount both now and before is equal. But if the sea was salty from the start, it will remain to assign a cause of its saltiness. Moreover, one should state why, if water was not borne aloft by evaporation from the very beginning, this happens now.

166. Then when he says, again, if it is maintained that an admixture of earth (357a15), he continues with the second opinion, and says that they who declared that mixing with earth to be the cause of the sea's saltiness fail to explain sufficiently why the sea is salty. For they claim that the earth has many tastes according to its various areas, so that the earth which the rivers transport to the sea mingles with the sea and makes it salty. But this seems unacceptable, namely, that the sea become salty through mixing with earth, while the rivers, which are smaller, are not salty. Indeed, if the vast quantity of the water of the sea is changed to salt by mixing with earth, the water of every river should, with even greater reason, be changed. For it is plain that the sea is an assemblage of all river waters—for the water of the sea differs from the water of rivers only by its saltiness - something that does not occur in the waters of rivers, but only in the place where all the rivers come together. And this does not seem possible, if the sole mixing of-earth transported by the rivers were to be the cause of saltiness.

167. third at it is equally absurd to suppose that anything has been explained (357a24), he disproves the third opinion with three arguments.

The first of these is taken from the fact that it assigned a non-evident cause of the saltiness. And he says that it is ridiculous for someone to think he is speaking plainly, when he says that the sea is the earth's sweat and is for that reason salty, as Empedocles said. This perhaps satisfies the demands of metaphorical utterances according to the manner of poets—for to speak in metaphors pertains to poets, and it is probable that Empedocles, who wrote in meter, so they say, uttered many things metaphorically. But such a manner of speaking is not sufficient for knowing the nature of a thing; because a natural thing is not revealed by the comparisons employed in a metaphor. For how does it come about that what a man drinks is sweet, whereas the sweat generated therefrom will be salty? The metaphor does not make it clear whether the sweat remains salty because of the separation of something that was very sweet in the drink, or by a mixing with something, as happens when water is strained through ashes, for by mixing with ashes it is made salty or bitter. And the same cause seems to be at work in the taste of urine, which is a superfluity collected in the bladder: for this residue becomes bitter and salty, although the moisture imbibed was sweet.

Now, if it is true that water becomes bitter because it is strained through lime, and likewise if along with urine is carried something of such virtue as to make it salty (for when urine is kept standing in chamber-pots a certain salty sediment is found to settle); and likewise with sweat, something similar adheres to it when the sweat is exuded from the flesh, which makes it salty, as though the moisture leaving the body in the form of sweat washed from the flesh a residue which makes the sweat salty; if, I say, this is so in these three cases, and if the metaphor about sweat is rightly taken, then it is plain that also in the case of the sea, the cause of saltiness will be something earthy mixing with the waters. But we know the cause of salt in the body of an animal, in sweat and in urine: it is the "hypostasis of food," i.e., the subsisting residue from what is appropriated as food by anything fed. The reason why it is salty is that it has not been digested. But what it is that can in like manner produce salt in the sea Empedocles has yet to say, since this is not manifest. And so it is plain that Empedocles sinned in this: that he did not clearly indicate the cause.

168. He presents the second argument at besides, how can the drying and warming of the earth (357b10); namely, that in spite of the drying up and warming of such a vast amount of water as is taken from the sea, nevertheless the whole water of the sea still remains salty. Now the portion raised away from the earth by evaporation is a submultiple of the water left on the earth (that is called submultiple which is to another as 1/2 is to double, or 1/3 to triple, and so forth). Hence it does not seem that the water of the sea, since it is a greater amount than the water borne up by evaporation can become salty from this, for sweat and urine, both of which are salty, are much less in volume than the moisture remaining in the body.

169. He presents the third argument at again, waiving the question of quantity (357b11), and says that Empedocles must be asked why it is that after being dried out in various small or large areas by the sun, the earth does not now sweat with a sweat that seems bitter: for if it was true in the beginning that the earth sweated a bitter moistness, it should be doing so even now. But this is not seen to be happening now: for we see that the earth, when moist, can be dried out, and after it is dried out, it does not undergo anything like this, i.e., sweating. Neither, therefore, was it possible in the primal generation of the world, when the earth was moist (because it was covered with water), for it to sweat through being dried out. Closer to the truth is the theory upheld by those who said that the sea is not the sweat of the earth but is water left after some portion of the earth did dry out. However, that the earth should sweat when moist, seems impossible. And so he finally concludes that the causes alleged for the saltiness of the sea are seen to elude reason.