Comparative Linguistics has two distinct approaches towards the study of languages; Typology and Generic. The aim of the former is to detect the universals, while the latter attempts to compile the history of languages.
Comparative linguist assumes one certain principle for all languages, which is the existence of similarities among them. These similarities are by no means accidental or borrowed. Thus it is assumed that these resemblances are indicators of a common source and the existing differences are the results of their development from a common original language. The comparative method enables us to reconstruct the principle features of the grammar and lexicon of the proto-language, which is a starting point to the historical description of the related languages. According to comparative linguistics, languages possess two dimensions; descriptive or linguistic and artistic-poetic. The linguistic dimension searches for a factor to transform a linguistic message to a work of art.
The comparison of the significant models in Indo-European languages makes it possible to reconstruct the languages to reach that common origin, and to define the verse poetry and the poetical prose, as a consistent tradition for communication among Indo-Europeans. Based on this comparison, it can be concluded that in traditional Indo-European societies, poetic language was the area of expertise of those who had poetic motivation, but in addition to the compose of poetry, had other duties such as priesthood, foretelling and eulogizing. The surviving terminologies in the branches of this language family, both in vocabulary and in the poets'' functional frame, are identical in west and east. Therefore, through these similarities not only can the social status of the poet be seen, but also the poetical terminology of the Indo-European family branches can be identified.
The following study attempts to reconstruct and describe the poetic language and its initial form according to the existing data, with an emphasis on the Indo-Iranian branch of the languages.