Zoroaster was one of those who was oppressed with the sight of evil.  But it was not outward evil which most tormented him, but spiritual evil,—­evil having its origin in a depraved heart and a will turned away from goodness.  His meditations led him to the conviction that all the woe of the world had its root in sin, and that the origin of sin was to be found in the demonic world.  He might have used the language of the Apostle Paul and said, “We wrestle not with flesh and blood,”—­that is, our struggle is not with man, but with principles of evil, rulers of darkness, spirits of wickedness in the supernatural world.  Deeply convinced that a great struggle was going on between the powers of light and darkness, he called on all good men to take part in the war, and battle for the good God against the dark and foul tempter.

Great physical calamities added to the intensity of this conviction.  It appears that about the period of Zoroaster, some geological convulsions had changed the climate of Northern Asia, and very suddenly produced severe cold where before there had been an almost tropical temperature.  The first Fargard of the Vendidad has been lately translated by both Spiegel and Haug, and begins by speaking of a good country, Aryana-Vaejo, which was created a region of delight by Ahura-Mazda (Ormazd).  Then it adds that the “evil being, Angra-Mainyus (Ahriman), full of death, created a mighty serpent, and winter, the work of the Devas.  Ten months of winter are there, two months of summer.”  Then follows, in the original document, this statement:  “Seven months of summer are (were?) there; five months of winter were there.  The latter are cold as to water, cold as to earth, cold as to trees.  There is the heart of winter; there all around falls deep snow.  There is the worst of evils.”  This passage has been set aside as an interpolation by both Spiegel and Haug.  But they give no reason for supposing it such, except the difficulty of reconciling it with the preceding passage.  This difficulty, however, disappears, if we suppose it intended to describe a great climatic change, by which the original home of the Aryans, Aryana-Vaejo, became suddenly very much colder than before.  Such a change, if it took place, was probably the cause of the emigration which transferred this people from Aryana-Vaejo (Old Iran) to New Iran, or Persia.  Such a history of emigration Bunsen and Haug suppose to be contained in this first Fargard (or chapter) of the Vendidad.  If so, it takes us back further than the oldest part of the Veda, and gives the progress of the Aryan stream to the south from its original source on the great plains of Central Asia, till it divided into two branches, one flowing into Persia, the other into India.  The first verse of this venerable document introduces Ormazd as saying that he had created new regions, desirable as homes; for had he not done so, all human beings would have crowded into this Aryana-Vaejo.  Thus in the very first verse of the Vendidad appears