In an examination of word-phrases A. Meillet stated long ago: “Des mots comme oui, non représentent le plus haut degré d'abstraction que puisse atteindre ainsi une réponse consistant en un seul mot.” As has been repeatedly pointed out, the classical Indo-European languages did not have any exact equivalent of this abstract method of expression. The majority of the modern languages on the other hand have arrived at these convenient “special expletive interjections”. Hindi nahîn, like the cognate Marathi nâhĩ, Gujerati nahi(m), etc. typifies this development of most modern Indo-European languages both syntactically and formally: it is used as an equivalent of “no” (though it may serve also as negative adverb), and it represents an enlargement of the old Indo-European negative particle, Sanskrit na. This formal and syntactic transformation of Sanskrit na into modern nahîn has been variously explained. The standard theories involve the addition to the negative particle of some part of a substantive verb, a development by no means isolated in the Indo-European languages. They may be summarized as follows:—
I. Theories in which parts of the verb as- “to be” are added.
(a) Kellogg stated: “The common negative nahîn, Braj nâhi has arisen from the combination of the negative na with the 3rd singular âhi of the substantive verb.
(b) S. K. Chatterji thinks that *asati based on Sanskrit asti may have been added to na.
(c) Dwijendranath Basu believes that only a derivation from na + âsit can account for the Bengali forms. Similar explanations were given also by Sen and others.