[...] parallelisms in drift may operate in the phonetic as well as in the morphological sphere, or they may affect both at the same time.
- Sapir (1921), a pag.172

[...] phonetic laws have their exceptions, but [...] these exceptions are more apparent than real. They are generally due to the disturbing influence of morphological groupings or to special psychological reasons which inhibit the normal progress of the phonetic drift.
- Sapir (1921), a pag.179

It is remarkable with how few exceptions one need operate in linguistic history, aside from 'analogical leveling' (morphological replacement).
- Sapir (1921), a pag.179

Every linguist knows that phonetic change is frequently followed by morphological rearrangements, but he is apt to assume that morphology exercises little [...] influence on the course of phonetic history. I am inclined to believe that our [...] tendency to isolate phonetics and grammar [...] is unfortunate.
- Sapir (1921), a pag.183

[...] particular variations won through because they [...] allowed the general phonetic drift to take its course without unsettling the morphological contours of the language. [...] The general drift seizes upon those individual sound variations that help to preserve the morphological balance or to lead to the new balance [...]
- Sapir (1921), a pag.186

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

A morphological feature that appears as the incidental consequence of a phonetic process, like the English plural with modified vowel, may spread by analogy no less readily than old features that owe their origin to other than phonetic causes.
- Sapir (1921), a pag.189