This extraction of components can be performed directly upon the contrasting segments in each environment, independently of how they are formed, and can indeed serve as a criterion for grouping complementary segments into phonemes. This is so because once a particular component, in combination with others, replaces a phoneme, that component will occur in every position in which the phoneme had occurred, and in each of these positions it will indicate the occurrence of the speech feature it represents; these unit-length components would not be set up with various definitions in various positions (i.e.with positional variants) because the chief purpose in setting them up is to indicate which speech feature occur characteristically every time a phoneme occurs.
- Harris (1951), a pag.148