It must be carefully noted […] that the reach of phonetics, its power to penetrate to the heart of its facts and accounts for them, is only limited. There is always an element in linguistic change which refuses scientific treatment: namely, the action of the human will. The work is all done by human beings, adapting means to ends, under the impulse of motives and the guidance of habits which are the resultant of causes so multifarious and obscure that they elude recognition and defy estimate.
- Whitney (1875), a pag.73

Not one item of any existing tongue is ever uttered except by the will of the utterer; not one is produced, not one that has been produced or acquired is changed, except by causes residing in the human will, consisting in human needs and preferences and economies.
- Whitney (1875), a pag.311

One great reason why men are led to deny the agency of the human will in the changes of speech is that they see so clearly that it does not work consciously toward that purpose.
- Whitney (1875), a pag.146-147

Our tracing of the etymology of a word is the following up of a series of acts of name-making, consisting chiefly in the new applications of old material […] And every one of those acts was one of choice, involving the free working of the human will; only under the government, as always and everywhere, of conditions and motives.
- Whitney (1875), a pag.143