There is a special method for the expression of relations [...] This is the method of 'concord' or of like signaling. It is based upon the same principle as the password or label.
- Sapir (1921), a pag.114

Not that sound-echo [...] is necessary to concord, though in its most typical and original forms concord is nearly always accompanied by sound repetition [...] words (elements) that belong together, [...] are outwardly marked by the same or functionally equivalent affixes.
- Sapir (1921), a pag.114

Psychologically the methods of sequence and accent lie at the opposite pole to that of concord. Where they are all for implication [...] concord is impatient of the least ambiguity but must have its well-certificated tags at every turn. Concord tends to dispense with order.
- Sapir (1921), a pag.116