IV. The bear, which places itself upon one side, is the Median Empire, smaller than the Chaldean, as the bear is smaller and less formidable than the lion. The crouching on one side is obscure. It is explained by some as implying that it was lower in exaltation than the Babylonian Empire; by others that "it gravitated, as regards its power, only towards the countries west of the Tigris and Euphrates."[501] The meaning of the "three ribs in its mouth" is also uncertain. Some regard the number three as a vague round number; others refer it to the three countries over which the Median dominion extended--Babylonia, Assyria, and Syria; others, less probably, to the three chief cities. The command, "Arise, devour much flesh," refers to the prophecies of Median conquest,[502] and perhaps to uncertain historical reminiscences which confused "Darius the Mede" with Darius the son of Hystaspes. Those who explain this monster as an emblem, not of the Median but of the Medo-Persian Empire, neglect the plain indications of the Book itself, for the author regards the Median and Persian Empires as distinct.[503] V. The leopard or panther represents the Persian kingdom.[504] It has four wings on its back, to indicate how freely and swiftly it soared to the four quarters of the world. Its four heads indicate four kings. There were indeed twelve or thirteen kings of Persia between B.C. 536 and B.C. 333; but the author of the Book of Daniel, who of course had no books of history before him, only thinks of the four who were most prominent in popular tradition--namely (as it would seem), Cyrus, Darius, Artaxerxes, and Xerxes.[505] These are the only four names which the writer knew, because they are the only ones which occur in Scripture. It is true that the Darius of Neh. xii. 22 is not the Great Darius, son of Hystaspes, but Darius Codomannus (B.C. 424-404). But this fact may most easily have been overlooked in uncritical and unhistoric times. And "power was given to it," for it was far stronger than the preceding kingdom of the Medes.