The Persian translator and commentator is said to be the fifth Sassan, who lived in the time of the Persian king Khusro-Parviz, a contemporary of the Roman emperor Heraclius, and died only nine years before the destruction of the ancient Persian monarchy, or in the year 643 of our era. It must be presumed that the five Sassans, the first of whom was a contemporary of Alexander, 323 years before Christ, were not held to be immediate successors to each other, but only in the same line of descent; otherwise an interval of 946 years, from Alexander to Parviz, comprehending the reign of thirty-one Arsacides and twenty-two Sassanian princes, would be given to no more than five individuals, which absurdity ought not to be attributed to the commentary of the Desátir. In general, so common is it with Asiatics to deal with names of celebrity as if they were generic names, that it is very frequently impossible to be positive about the true author of a work. There appears in the present case nothing to prevent us from placing the translator and commentator of the Desátir (whether a Sassan or not) in the seventh century of our era. The translation and commentary of the Desátir are written in what the best judges consider as very pure Persian, though ancient, without any mixture whatever of words of Arabic or Chaldean origin, and conformable to the grammatical system of modern Persian. But when was the latter formed?――As the opinion upon this epoch involves that upon the age of the composition itself, I shall be permitted to take a rather extensive historical view of this part of the question. Setting aside the Mahabadian kings mentioned in the Desátir and Dabistán, we know that Gilshah, Hoshang, Jamshid (true Persian names) are proclaimed by all Orientalists as founders of the Persian empire and builders of renowned cities in very remote times. This empire comprised in its vast extent different nations, speaking three principal languages, the Zand, Pehlevi, and Parsi. Among these nations were the _Persæ_, “Persians,” properly and distinctively so called. We are informed by Herodotus[55] that there were different races of Persæ, of whom he enumerates eleven. Those who inhabited originally _Fars_, _Farsistan_, _Persis_,[56] a country double the extent of England, and gave their name to the whole empire, certainly spoke their own idiom, the _Parsi_ or _Farsi_. A national language may vary in its forms, but never can be destroyed as long as any part of the nation exits; can we doubt that the Persians who, once the masters of Asia, although afterwards shorn of their power, never ceased to be independent and formidable, preserved their language to our days?