Anaximander affirms that the sea is the remainder of the primogenial humidity, the greatest part of which being dried up by the fire, the influence of the great heat altered its quality. Anaxagoras, that in the beginning water did not flow, but was as a standing pool; and that it was burnt by the motion of the sun about it, by which the oily part of the water being exhaled, the residue became salt and bitter. Empedocles, that the sea is the sweat of the earth burnt by the sun. Antiphon, that the sweat of that which was hot was separated from the other parts which were moist; these by seething and boiling became bitter, as happens in all sweats. Metrodorus, that the sea was strained through the earth, and retained some part of the density thereof; the same is observed in all those things which are strained through ashes. The schools of Plato, that the element of water being compacted by the rigor of the air became sweet, but that part which was exhaled from the earth, being enfired, became of a brackish taste. CHAPTER XVII. OF TIDES, OR OF THE EBBING AND FLOWING OF THE SEA. Aristotle and Heraclides say, they proceed from the sun, which moves and whirls about the winds; and these falling with a violence upon the Atlantic, it is pressed and swells by them, by which means the sea flows; and their impression ceasing, the sea retracts, hence they ebb. Pytheas the Massilian, that the fulness of the moon gives the flow, the wane the ebb. Plato attributes it all to a certain oscillation of the sea, which by means of a mouth or orifice causes the alternate ebb and flow; and by this means the seas do rise and flow contrarily. Timaeus believes that those rivers which fall from the mountains of the Celtic Gaul into the Atlantic produce a tide. For upon their entering upon that sea, they violently press upon it, and so cause the flow; but they disemboguing themselves, there is a cessation of the impetuousness, by which means the ebb is produced. Seleucus the mathematician attributes a motion to the earth; and thus he pronounceth that the moon in its circumlation meets and repels the earth in its motion; between these two, the earth and the moon, there is a vehement wind raised and intercepted, which rushes upon the Atlantic Ocean, and gives us a probable argument that it is the cause the sea is troubled and moved. CHAPTER XVIII. OF THE HALO, OR A CIRCLE ABOUT A STAR. The halo or circle is thus formed. A thick and dark air intervening between the moon or any other star and our eye, by which means our sight is dilated and reflected, when now our sight is incident upon the outward circumference of the orb of that star, there presently seems a circle to appear. This circle thus appearing is called the ἅλως or _halo_; and there is constantly such a circle seen by us, when such a density of sight happens. BOOK IV. Having taken a survey of the general parts of the world, I will take a view of the particular members of it. CHAPTER I.