With only principle I to guide us, any of the initial stops could be identified with any of the final ones, so that there would be a total of 720 different ways of “phonemicizing” the data (inizial [p'] with any of the six final stops; then the inizial [t'] with any of the five still unassigned final stops; and so on). The principle of phonetic similarity puts an end to this range of choice, and the principle of neatness of pattern offers firm support in the same direction.
- Hockett (1958), Pag. 109