5. Again, however, Polybius makes an incorrect assertion, in stating that the whole length of Europe is unequal to that of Africa and Asia taken together. He tells us “that the entrance at the Pillars corresponds in direction to the equinoctial west, and that the Don flows from the summer rising, consequently the length of Europe is less than that of Asia and Africa taken together by the space between the summer rising[689] and the equinoctial rising,[690] since Asia occupies the eastern portion of the northern semicircle. Now, in addition to the obscurity which Polybius throws over subjects which might have been simply stated, it is false that the river Don flows from the summer rising. For all who are acquainted with these localities inform us that this river flows from the north into the Mæotis, so that the mouth of the river lies under the same meridian as that of the Mæotis; and so in fact does the whole river as far as is known.[691] 6. Equally unworthy of credit is the statement of those who tell us, that the Don rises in the vicinity of the Danube, and flows from the west; they do not remember that between these are the Dniester, the Dnieper, and the Bog, all great rivers, which flow [into the Euxine Sea]; one runs parallel to the Danube, the other two to the Don. Now if at the present day we are ignorant of the sources both of the Dniester, and also of the Dnieper and Bog, the regions farther north must certainly be still less known. It is therefore a fictitious and idle assertion, that the Don crosses these rivers, and then turns northward on its way to discharge itself into the Mæotis, it being well known that the outlets to this river are in the most northern and eastern portions of the lake.[692] No less idle is the statement which has also been advanced, that the Don, after crossing the Caucasus, flows northward, and then turns towards the Mæotis.[693] No one, however, [with the exception of Polybius,] made this river flow from the east. If such were its course, our best geographers would never have told us that its direction was contrary to that of the Nile, and, so to speak, diametrically opposite thereto, as if the course of both rivers lay under the same meridian.