Speech is a human activity that varies without assignable limit as we pass from social group to social group, because it is a purely historical heritage of the group, the product of long-continued social usage.
- Sapir (1921), Pag. 4

[...] speech is a non-instinctive, acquired, 'cultural' function.
- Sapir (1921), Pag. 4

[...] there is all the difference in the world between [...] involuntary expression of feeling and the normal type of communication of ideas that is speech.
- Sapir (1921), Pag. 5

Speech [...] is an extremely complex and ever-shifting network of adjustements - in the brain, in the nervous system, and in the articulating and auditory organs- tending towards the desired end of communication.
- Sapir (1921), Pag. 9

Physiologically, speech is an overlaid function, or [...] a group of overlaid functions. It gets what service it can out of organs and functions, nervous and muscular [...]
- Sapir (1921), Pag. 9

[...] the cycle of speech [...] as a purely external instrument, begins and ends in the realm of sounds.[...] the typical course of this process may undergo endless modifications or transfers into equivalent systems without thereby losing its essential formal characteristics.
- Sapir (1921), Pag. 18

[...] by 'speech' we shall henceforth mean the auditory system of speech symbolism, the flow of spoken words [...]
- Sapir (1921), Pag. 24

Speech is [...] constantly tightening and loosening its sequences. In its highly integrated forms[...] the 'energy' of sequence is largely locked up in complex word formations, it becomes transformed into a kind of potential energy that may not be released for millennia.
- Sapir (1921), Pag. 112

Like all human institutions, speech is too variable and too elusive to be quite safely ticketed.
- Sapir (1921), Pag. 121