It is a very notable characteristic of this Iranian theology, that although the forces of good and evil are co-extensive and formally balanced, in potency they are not quite equal. The balance of force is just a little on the side of the Good Spirit. And this advantage appears in man. Zoroaster said, 'No earthly man with a hundredfold strength does so much evil as Mithra with heavenly strength does good;' and this thought reappears in the Parsî belief that the one part of paradisiac purity, which man retained after his fall, balances the ninety-nine parts won by Ahriman, and in the end will redeem him. For this one divine ray preserved enables him to receive and obey the Avesta, and to climb to heaven by the stairway of three vast steps--pure thought, pure word, pure deed. The optimistic essence of the mythology is further shown in the belief that every destructive effort of Ahriman resulted in a larger benefit than Ormuzd had created. The Bull (Life) destroyed, man and animal sprang into being; the man destroyed, man and woman appeared. And so on to the end. In the last quarter of the 12,000 years for which Ahriman was condemned, he rises to greater power even than Ormuzd, and finally he will, by a fiery comet, set the visible universe in conflagration; but while this scheme is waxing to consummation Ormuzd will send his holy Prophet Sosioch, who will convert mankind to the true law, [16] so that when Ahriman's comet consumes the earth he will really be purifying it. Through the vast stream of melted metals and minerals the righteous shall pass, and to them it will be as a bath of warm milk: the wicked in attempting to pass shall be swept into the abyss of Duzhak; having then suffered three days and nights, they shall be raised by Ormuzd refined and purified. Duzhak itself shall be purified by this fire, and last of all Ahriman himself shall ascend to his original purity and happiness. Then from the ashes of the former world shall bloom a paradise that shall remain for ever.