In practice phonetic laws have their exceptions, but [...] these [...] are generally due to the disturbing influence of morphological groupings [...] which inhibit the normal progress of the phonetic drift.
- Sapir (1921), Pag. 180

[...] often the phonetic drift is[...] not so much a movement toward a particular set of sounds as toward particular types of articulation.
- Sapir (1921), Pag. 181

There is [...] good evidence to show that there are general phonetic drifts toward particular sounds.
- Sapir (1921), Pag. 181

Indians find hopelessly difficult sounds and sound combinations that are simple to us; one language encourages a phonetic drift that another does everything to fight.
- Sapir (1921), Pag. 183

A preservative tendency [...] sets in when a too serious morphological unsettlement is threatened by the main drift. I do not imagine [...] that [...] this purely schematic statement does justice to the complex forces that guide the phonetic drift.
- Sapir (1921), Pag. 186

If all the phonetic changes brought about by the phonetic drift were allowed to stand, [...] most languages would present such irregularities of morphological contour as to lose touch with their formal ground-plan.
- Sapir (1921), Pag. 187

We may suppose that individual variations arising at linguistic borderlands [...] have gradually been incorporated into the phonetic drift of a language.
- Sapir (1921), Pag. 200