And the fourth kingdom shall be strong as iron,.... This is not the kingdom of the Lagidae and Seleucidae, the successors of Alexander, as some have thought; for these are designed by the thighs in the third kingdom; and, besides, the kingdom of Christ was to arise in the time of this fourth kingdom, which it did not in that; nor the kingdom of Gog, or the empire of the Turks, as Saadiah, Aben Ezra, and Jarchi; but the Roman empire, which is compared to iron for its strength, firmness, and duration in itself; and for its power over other nations; and also for its cruelty to the Jews above all others, in utterly destroying their city, temple, and nation: forasmuch as iron breaketh in pieces and subdueth all things; so this kingdom has subdued and conquered all others; not the Jews only, but the Persians, Egyptians, Syrians, Africans, French, Germans, yea, all the world: and as iron that breaketh, or "even as iron breaketh all these", shall it break in pieces, and bruise; all nations and kingdoms; hence Rome has been called the mistress of the world, and its empire in Scripture is called the whole world, Luk 2:1.