V uvodu pišejo: Too little historical or archaeological evidence is available to reconstruct definitively the earliest emergence of Iranian-speaking communities. There are, however, striking linguistic and ideological similarities between the extant texts of Old Iranian and those preserved in the closely related dialects of Old Indo-Aryan recorded in the regions to the east and west of the Iranian plateau.
V prvi lekciji pa protislovno pravijo: The Gathas of Zarathustra are the earliest extant collection of an Old Iranian language. In form and stylistic technique, they are not unlike the larger collections of hymns preserved in the Indian Rigveda, since their author was a sacrificial priest reared in the same traditional methods of Indo-Iranian liturgical composition. Much of their grammar and vocabulary, however, is unique, and their strikingly different mythology gives a great deal more weight to theodicy and moral code than anything in any Indian work contemporary to the period. These differences often render comparison with the Indian texts well-nigh (skoraj) impossible; interpretation is often difficult, given the total absence of other contemporary works in Old Iranian dialects. Fortunately, Zarathustra's composition and ideology are rigorously unified and consistent and can at least be understood, albeit to a limited extent, within the framework of the hymns themselves.