We therefore see no reason for believing that important Christian or Mohammedan ideas have been interpolated into the old Zoroastrian religion. The influence has been in the other direction. Relying then, though with caution, on what Dr. Edward Roth says, that "the certainty of our possessing a correct knowledge of the leading ancient doctrines of the Persians is now beyond all question," we will try to exhibit so much of the system as is necessary for appreciating its doctrine of a future life. In the deep background of the Magian theology looms, in mysterious obscurity, the belief in an infinite First Principle, Zeruana Akerana. According to most of the scholars who have investigated it, the meaning of this term is "Time without Bounds," or absolute duration. But Bohlen says it signifies the "Untreated Whole;" and Schlegel thinksit denotes the "Indivisible One." The conception seems to have been to the people mostly an unapplied abstraction, too vast and remote to become prominent in their speculation or influential in their faith. Spiegel, indeed, thinks the conception was derived from Babylon, and added to the system at a later period than the other doctrines. The beginning of vital theology, the source of actual ethics to the Zoroastrians, was in the idea of the two antagonist powers, Ormuzd and Ahriman, the first emanations of Zeruana, who divide between them in unresting strife the empire of the universe. The former is the Principle of Good, the perfection of intelligence, beneficence, and light, the source of all reflected excellence. The latter is the Principle of Evil, the contriver of misery and death, the king of darkness, the instigator of all wrong. With sublime beauty the ancient Persian said, "Light is the body of Ormuzd; Darkness is the body of Ahriman." There has been much dispute whether the Persian theology grew out of the idea of an essential and eternal dualism, or was based on the conception of a partial and temporary battle; in other words, whether Ahriman was originally and necessarily evil, or fell from a divine estate.