[...] if we substitute such words as 'man' and 'chick' for 'farmer' and 'duckling', we obtain a new material content[...] but not [...]a new structural mold.[...] the two sentences fit precisely the same pattern[...] differing only in their material trapping[...] they express identical relational concepts in an identical manner.
- Sapir (1921), a pag.85

Change any [...] feature of the sentence and it becomes modified [...] in some purely relational, non-material regard. If 'the' is omitted ( 'farmer kills duckling' [...] ) the sentence becomes impossible;[...] there is no relation established between either of them and what is already in the minds of the speaker and his auditor.
- Sapir (1921), a pag.85

Number is evidently felt by those who speak English as involving a necessary relation, otherwise there would be no reason to express the concept twice, in the noun and in the verb.
- Sapir (1921), a pag.87

Time also is clearly felt as a relational concept; if it were not, we should be allowed to say 'the farmer killed-s' to correspond to 'the farmer kill-s'.
- Sapir (1921), a pag.87

[...] I can radically disturb the relational cut of the sentence by changing the order of its elements. If [...] 'farmer' and 'kills' are interchanged, the sentence reads 'kills the farmer the duckling' [...]
- Sapir (1921), a pag.87

No proposition [...] is humanly possible without a tying on [...] to the concrete world of sense. In every intelligible proposition [...] such relational concepts must be expressed as moor the concrete concepts to each other and construct a definite, fundamental form of proposition.
- Sapir (1921), a pag.93

[...] there must be no doubt as to the nature of the relations that obtain between the concrete concepts. We must know what concrete concept is directly or indirectly related to what other and how.
- Sapir (1921), a pag.93

If I wish to communicate an intelligible idea about a farmer, a duckling, and the act of killing, it is not enough to state the linguistic symbols for these concrete ideas in any order [...] trusting that the hearer may construct some kind of a relational pattern out of the general possibilities of the case. The fundamental syntactic relations must be unambiguously expressed.
- Sapir (1921), a pag.94