[…] he [child] does not readily catch the idea that a set of sounds belongs to and represents a thing- any more than, when older, the idea that a series of written characters represents a word […].
- Whitney (1875), Pag. 11

[…] of the indefinite number of distinguishable sounds which it [voice] can produce, only a fraction, of twelve to fifty, are put to use in any one language; and there is nothing in the selection to characterize a race, or to be used […] for ethnological distinction: from among the many possible, these have chanced to be taken; mainly the sounds easiest to make, and broadly distinguished from one another.
- Whitney (1875), Pag. 293-294

[…] the “vocal chords,” are capable of being brought close together in the middle of the passage, and made tense, so that the passing current of air sets them in vibration; and this vibration, communicated to the air, is reported to our ears as sound.
- Whitney (1875), Pag. 59

[…] what is universally true between related languages: their sounds, in corresponding words, are by no means always the same; they are diverse, rather, but diverse by a constant difference; there exists between them as a fixed relation, though it is not one of identity. Hence, in the comparison of two languages, a first point to which attention has to be directed is this: what sounds in the one, vowel or consonantal, correspond to what sounds in the other.
- Whitney (1875), Pag. 58

Above the vibrating reed-apparatus is set, after the fashion of a sounding-box, the cavity of the pharynx, with that of the mouth, and the nasal passage; and movements of the throat and mouth-organs under voluntary control so alter the shape and size of this box as to give to the tone produced a variety of characters, or to modify it into a variety of tones- which are the sounds of our spoken alphabet.
- Whitney (1875), Pag. 59-60

Nothing is more frequent than for a language to take a dislike, as it were, to some particular sound or class of sounds, and to get rid of it by conversion into something else.
- Whitney (1875), Pag. 72

One sound passes into another that is physically akin with it: that is to say, that is produced by the same organs; or otherwise in a somewhat similar manner; and the movement of transition follows a general direction, or else is governed by specific causes.
- Whitney (1875), Pag. 58