Iran was divided into fertile land and deserts; next to the most luxuriant growth lay wide tracts, in which heat or cold, morass or drought, storms of sand or of snow, made life and agriculture impossible. These contrasts were most striking on the upper Oxus, in Sogdiana and Margiana. Hence it came to pass that in Bactria the ancient belief in the struggle of the good and evil spirits made an essential advance. The old gods and spirits, the ancient worship of fire, were not indeed overthrown by the doctrine of Zarathrustra; on the contrary, the struggle between the good and evil powers was spread over the whole of nature, and the means of repelling the evil ones were increased. The good and evil spirits were respectively ranged under chiefs, on the counter-operation of whom and their spirit-armies rests the life of nature; and on this life depends the life of man. Henceforth man must not merely keep the evil ones from himself, he must take part in the struggle of the good against the evil powers, increase so far as he can the good creation which now belongs to Auramazda and has proceeded from him; and thus restrict the sphere in which the evil spirit exercises his power. After death he will receive the reward of his conflict; and if in and through this struggle he has been made a participator in the nature of the pure and bright deities, he will continue to live in their heaven of light. This development of the old Arian views and reform of the religion received the impulse which eventually called it into life at the time when Vistaçpa was king of Bactria. It must have taken place about the year 1000 B.C., _i.e._ about the time when the Brahmans on the Ganges came to reform their ancient faith, and exalted Brahman above Indra and the ancient deities. From the idea of this new god, in which the power of the Holy and the world-soul were equal factors, the Brahmans arrived at a sharp distinction between spirit and matter. Their ethics, beginning with the rejection of nature, could not but require the annihilation of the body as their final goal, and this led to the vain pursuit of impossibilities, to the ascetic suicide of body and soul. The doctrine of Zarathrustra does not recognise the contradiction of spirit and matter. The good God has not created the world in order to entangle men in evil and wickedness, but in order to give to it and to mankind life and increase. It is only one side of nature, not the whole of it, and that side harmful to men, which has proceeded from evil, and this evil does not come from the good, but from the wicked spirit. Evil is here limited to gloom, desolation, drought and death. As it is this part, and this only in nature, which has to be removed, man is not called upon to lay aside his whole nature, but on the contrary to rejoice in the beneficial side of it. This he must tend and strengthen in himself, while he keeps the harmful side at a distance, struggles