[…] a far grosser error, that of actually identifying speech with thought and reason […] nothing but the most imperfect comprehension of language can account for a blunder so radical […] Language is, upon the whole, the most conspicuous of the manifestations of man’s higher endowments, and the one of the widest and deepest influence on every other; and the superiority of man’s endowments is vaguely known as reason- and this is the whole ground of the assertion of identity. There are many faculties which go to the production of speech. And we have only to take the most normally endowed human being and cut off artificially the avenue of a single class of sensuous impressions, those of hearing, and he will never have any speech. If speech, then, is reason, reason will have to be defined as a function of the auditory nerve.
- Whitney (1875), a pag.304-305

Language is in no way to be separated from the rest [other faculties]: it is in some respects very unlike them; but so they are unlike one another; if it be the one most fundamentally important, most highly characteristic, most obviously the product and expression of reason, that is only a difference of degree.
- Whitney (1875), a pag.280