THIS empire, extending from Egypt to India, was divided into provinces, each under a satrap (Viceroy) with full military and civil powers. The administration of these satraps was liable to examination at any time by officials called " The King's Eyes." The national army, too, remained under the king's direct orders, as did the garrisons stationed at strategic points commanding the grand trunk roads leading from Susa, the capital, in Persia, to the farthest provinces. The best security for the permanence of the empire was the loyalty of the ruling classes and the contentment of the subjects. The Persian was tolerant to other religions, as the Jews, who were restored to Jerusalem from Babylon, could testify and he also encouraged agriculture and trade. It was no wonder that, in spite of the feebleness of later rulers, the structure held firm until Alexander's coming in 331 B.C. Not until the golden age of the Roman Empire in the second century A.D. did the world enjoy a government as just and as gentle. The kinder rule of the Persians was no accident, but arose partly from the teaching of their religion. A teacher, Zoroaster, had taught them that the world was the scene of an everlasting struggle between the forces of light and of darkness, between Ahura-Mazda, who manifested himself in fire, and Ahriman, creator of evil in the world and in the heart of man. It was each man's duty to take his stand with Mazda, and to help to make the world fruitful and his own heart clean. This sublime belief was later perverted by the Magians, the Persian priests, who insisted on the necessity of avoiding the pollution caused by contact with anything dead. It was considered wicked to burn or to bury the dead, and they were exposed on " Towers of Silence " for the vultures to devour, just as they are by the Parsees in India to-day. Later still, the people worshipped the impure gods of the Babylonians. Their practical code was summed up in the admonition, " To ride, to draw the bow, and to speak the truth."