the Sad-der-Bundehesh, puts the period of the conflict between the good and evil deity at 6000 years, and places Zarathrustra exactly in the middle of it; he was created 3000 years after the period of Gayo maretan, and 3000 years before his own resurrection.[150] Hence it is clear that the formation of these cycles rose among the priests of Iran from the necessity of limiting the period of the old and new law, and of conflict between the good and evil spirits, and the desire to fix the date of the more successful repulse of evil which came in with Zarathrustra. The abbreviation of the period of Yima shows us that the cycles in the Bundehesh do not throughout agree with those of the Avesta. But it is sufficient to establish the fact that periods of 3000 years were in use, and that Zarathrustra appeared at the beginning of a new millennium, in order to understand that the Persians could speak to the Greeks of millenniums in this sense, and of one or two cycles which had elapsed since Zarathrustra's time. The idea and tendency of such a scheme for the history of the world are easily understood: these periods of 3000 years, which can be increased or diminished without alteration of the sense, have only a dogmatic value. We cannot obtain from them any chronological date for the appearance of Zarathrustra, nor can we obtain such a date by the attempt to go back from the chronological statements in recent Parsee works to the older periods. We may leave unnoticed the assertion in the book of Arda Viraf that the true faith had existed in purity for 300 years down to the time that Alexander came into Iran (p. 50), which would thus bring Zarathrustra into the seventh century B.C. The Bundehesh allows 460 years for the reigns of the Sassanids, 246 for the Askanids, _i.e._ the Arsacids, 16 for Alexander, before whom come Darai the son of Darai with 14 years, Darai Chirazatan with 12, Huma (a queen) with 30, Vohumano with 112, and Vistaçpa with 90,--all subsequent to the appearance of Zarathrustra.[151] According to this, 996 years elapsed between Zarathrustra and the fall of the Sassanids, and he would thus, if we reckon from the battle of Nahavend (640 A.D.), be placed in the year 356 B.C., in the reign of Artaxerxes Ochus. But even if we alter the incorrect items in the text of the Bundehesh in accordance with our better knowledge, we do not arrive at any result which is even apparently certain. The dominion of the Sassanids, down to the date of the battle, did not last 460 but only 414 years; on the other hand, the Arsacids reigned for 476 years, not for 264.[152] The empire of Alexander, if we add the reigns of the Seleucidæ to his own, occupied 80 years instead of 14, and if in the place of the 26 years of the two Darais of the Bundehesh, who represent the kingdom of the ancient Achæmenids, we put the old Persian kingdom with 229 years, and add to these items the numbers given in the Bundehesh for Huma, Vohumano, and