World Wide Study Bible
a Bible passage
5. bear—symbolizing the austere life of the Persians in their mountains, also their cruelty (Isa 13:17, 18; Cambyses, Ochus, and other of the Persian princes were notoriously cruel; the Persian laws involved, for one man's offense, the whole kindred and neighborhood in destruction, Da 6:24) and rapacity. "A bear is an all-devouring animal" [Aristotle, 8.5], (Jer 51:48, 56).
raised … itself on one side—but the Hebrew, "It raised up one dominion." The Medes, an ancient people, and the Persians, a modern tribe, formed one united sovereignty in contrast to the third and fourth kingdoms, each originally one, afterwards divided. English Version is the result of a slight change of a Hebrew letter. The idea then would be, "It lay on one of its fore feet, and stood on the other"; a figure still to be seen on one of the stones of Babylon [Munter, The Religion of Babylonia, 112]; denoting a kingdom that had been at rest, but is now rousing itself for conquest. Media is the lower side, passiveness; Persia, the upper, active element [Auberlen]. The three ribs in its mouth are Media, Lydia, and Babylon, brought under the Persian sway. Rather, Babylon, Lydia, and Egypt, not properly parts of its body, but seized by Medo-Persia [Sir Isaac Newton]. Called "ribs" because they strengthened the Medo-Persian empire. "Between its teeth," as being much grinded by it.
devour much flesh—that is, subjugate many nations.