These highly respectable critics published their judgment upon the Mahabadian language before the comparison of several languages with the Sanscrit and between each other had been made by able philologers, creators of the new science of comparative philology. According to the latter, the proofs of the real affinity of language, that is, the proofs that two languages belong to the same family, are to be principally and can be properly deduced, from their grammatical system. Thus, for instance, the forms of the Greek and Latin languages are in several parts nearly identical with the Sanscrit, the first bearing a greater resemblance in one respect, the latter in another; the Greek verbs in _mi_, the Latin declension of some nouns appear, to use the expression of the illustrious author, “traced from each other (_calqués l’un sur l’autre_).” These two languages seem to have divided between them the whole system of the ancient grammar, which is most perfectly preserved in the Sanscrit. This language itself is probably, with the two mentioned, derived from a more ancient language; we meet in them three sisters recognised by their striking likeness. This, although more or less weakened and even obliterated in some features, remains upon the whole still perceptible in a long series of their relations: I mean in all those languages which are distinguished by the name of _Indo-germanic_, to which the Persian belongs. But, in deciding upon the affinity of languages, not only the grammatical forms are to be examined, but also the system of sounds is to be studied, and the words must be considered in their roots and derivations. The three critics mentioned agree that the language of the Desátir is very similar to the Persian or Deri, not only in grammar, but also in etymology; a great number of the verbal and nominal roots are the same in both. This similarity would, according to comparative philology, lead to the conclusion that either the one is derived from the other, or that both proceed from a common parent; but nothing hitherto here alleged can justify the supposition of invention, forgery, or fabrication of the so-called Mahabadian language.