Lecture 4 — Whether the sea always was and always will be.

We must now explain why the sea is salt, and ask whether it eternally exists as identically the same body, or whether it did not exist at all once and some day will exist no longer, but will dry up as some people think.

Every one admits this, that if the whole world originated the sea did too; for they make them come into being at the same time. It follows that if the universe is eternal the same must be true of the sea.

Any one who thinks like Democritus that the sea is diminishing and will disappear in the end reminds us of Aesop's tales. His story was that Charybdis had twice sucked in the sea: the first time she made the mountains visible; the second time the islands; and when she sucks it in for the last time she will dry it up entirely. Such a tale is appropriate enough to Aesop in a rage with the ferryman, but not to serious inquirers.

Whatever made the sea remain at first, whether it was its weight, as some even of those who hold these views say (for it is easy to see the cause here), or some other reason—clearly the same thing must make it persist for ever. They must either deny that the water raised by the sun will return at all, or, if it does, they must admit that the sea persists for ever or as long as this process goes on, and again, that for the same period of time that sweet water must have been carried up beforehand. So the sea will never dry up: for before that can happen the water that has gone up beforehand will return to it: for if you say that this happens once you must admit its recurrence. If you stop the sun's course there is no drying agency. If you let it go on it will draw up the sweet water as we have said whenever it approaches, and let it descend again when it recedes.

This notion about the sea is derived from the fact that many places are found to be drier now than they once were. Why this is so we have explained. The phenomenon is due to temporary excess of rain and not to any process of becoming in which the universe or its parts are involved. Some day the opposite will take place and after that the earth will grow dry once again. We must recognize that this process always goes on thus in a cycle, for that is more satisfactory than to suppose a change in the whole world in order to explain these facts. But we have dwelt longer on this point than it deserves.

159. After determining the nature of the sea, showing that it is the natural place of water, the Philosopher here inquires into its generation.

First, he indicates his intention (356b4), and says that we must speak about the salt of the sea, and furthermore, about whether the sea is eternal or whether there was a time when the sea was not, and there will be a time when the sea will not be, but will completely cease.

160. second at every one admits this (356b6), he pursues the proposition by disproving the theories of others on this matter:

first, he disproves the theories of the ancients;

second, he excludes their reason, at this notion about the sea is derived from the fact (356b30).

About the first he does two things.

First, he disproves the theories of the ancients about the sea's coming into existence (356b6) and says that some have thought that the sea has not always existed but began to exist at some time. They also posited that the entire world began to exist as the result of some process of generation and stated that the sea began with the world. This was not unreasonable, since, the sea being in a sense the place of water, which is one element, it must be among the principal parts of the world. Hence, whenever the world existed, the sea did. And therefore, just as they argue that, because the world was generated, the sea was generated, so we can argue conversely, that if the world is perpetual, so too is the sea. But that the world is perpetual, he presupposes from what he proved in the Physics and in On the Heavens—although this is false and alien to the faith, as was said above.

161. second at **any one who thinks like Democritus that the sea is diminishing **(356b9), he disproves the opinions of the ancients about the disappearance of the sea.

First he compares this theory to fables. And he says that to think that the sea will diminish in size and at length disappear, as Democritus said, is no different than the ideas in the fables of Aesop, who stated in a fable that Charybdis, a certain deep chasm in the sea, has twice absorbed the sea, in such a manner that previously water covered the entire earth, and this chasm imbibed enough water for the mountains to appear, having been uncovered from the water, and also the land between them; the second time it took in enough for islands to appear; the final time, it will swallow all the water of the sea, and thus there will everywhere remain dry land without the sea. But although to compose such a fable befits Aesop, the inventor of fables, who uttered this one when perhaps in a fit of anger with a porthmeum, i.e., some harbor or seashore, so that, being angry with the waters, he pretended that all waters were destined to be swallowed up, yet, the utterance of such tales is less fitting for philosophers seeking the truth.

162. second at whatever made the sea (356b17), he disproves the aforesaid theory with a reason. And he says that whatever be the cause on account of which water first surrounded the earth, it will necessarily remain forever: whether it be said that this happens on account of the heaviness of water, whose weight makes it abide beneath the air and above the earth (which, indeed, is the true and manifest cause), or whatever else the cause may be, nevertheless, because of this, it must be that, if the water of the sea was at some time on the earth, it remain forever. For otherwise, if this were not so, they would have to say that the evaporated water borne aloft by the sun, does not return again to earth (the opposite of which is plain in the case of rain). Or, if the elevated water returns, it must needs be either that the sea always abide, if water is forever borne aloft and returns, or that it abide so long as the phenomenon of water returning shall continue. Further, it will be necessary for that which is drinkable in water to be borne aloft by evaporation. Consequently, the sea will never grow dry in such an alternation—since the water will return once more to the sea. And it makes no difference whether this happens once, namely, that the elevated water descend again, or a number of times: for in either case, no water is lost. Because it could, however, be claimed that this alternating process will not last forever, if the movement of the sun were to cease, he therefore adds that if anyone should say that the motion of the sun will cease, there will be nothing left to cause the sea's drying up; but if the motion of the sun abides forever, then it will always be necessary that the sun, as it approaches some region of the earth, lift up water by evaporation, and, when it departs from that region, that the water should fall, by reason of the cold. And so it cannot be said that the sea will entirely dry out, whether the motion of the sun continues or ceases.

163. Then when he says, this notion about the sea (356b30), he dismisses the reason moving them to posit their theory. And he says that they took up this theory (namely, that the sea would become wholly dry, and that it began at some time to exist), because there are many places that seem drier now than formerly. But the cause of this passion has not been given before, namely, the fact that at certain determinate times an excess of water is produced, and not because the universe as a whole is in the process of becoming—although its parts are. Then, at other determinate times, the contrary will come to pass, namely, there will be an excessive drought. When this shall have come about, the land will again be dried out which had been covered with water by the previous excess of water. And it is necessary that this proceed always in a cyclic way, namely, that after an excess of water there be, at a definite time, an excess of dryness, and vice-versa. This is more reasonable than the theory that the whole heaven is undergoing change just because of certain particular changes taking place around the earth. And because this theory against which he has spoken appears reasonable on the surface, he remarks that his discussion has lingered longer on this point than it deserves.