or ZERDUSHT, the founder or remodeler of the religious belief of the Medians, is known to posterity only by the doctrines which he introduced. Of his personal history scarcely anything has been ascertained, though it is considered probable that he was a Median by birth. The period at which he flourished is also a matter of uncertainty, some maintaining that he lived in the reign of Darius Hystaspes; others, that he flourished under Cyaxares I. The religious doctrines which he inculcated are contained in the Zendavesta, and are in all probability merely a development of the previous belief of his countrymen. The leading principle of his system is the Dualism so common in the eastern theologies. He maintained the eternal existence of two principles opposed to each other, Ormuzd, the principle of light and purity; and Ahriman, the father of evil and the source of darkness and impurity. Between these an irreconcilable contest is for ever waged. They are the creators of all things. Ormuzd created six immortal spirits, who dwell nearest him; then twenty-eight subordinate spirits, symbolical of the months and days; and, finally, the souls of men. Ahriman, on his part, produced six supreme spirits of evil, and then innumerable fiends of less power. For 3000 years Ormuzd was sole ruler, happy in the contemplation of his own perfections. At the end of that period he created the various beings who derived their existence from him, and who lived under his rule in innocence and consequent happiness, during another period of 3000 years. This golden age of innocence is succeeded by a period of equal length, during which the contest between Ormuzd and Ahriman is waged with varying success, a sort of brazen age, in which good and evil strive for the mastery; and this in its turn gives place to the age of iron, in which evil is on the whole predominant. When the 3000 years of the iron age have expired, the dominion of Ahriman is at an end; he acknowledges the supremacy of the principle of good, and all who have been subject to Ormuzd return to the primeval state of happiness. His moral doctrines, like those of most oriental systems, taught that the souls of men were the seat of a struggle between two principles, emanations respectively from Ormuzd and Ahriman; and that those who endeavoured to serve the one, were admitted on their death into the dwelling of the happy; while those who obeyed the other, were banished to a region of woe.