Purva-Mimamsa in its Sources c19.s1.2

c19.s1.2

Thus then, if the meaning of the Words can be known only when they occur in Injunctive Sentences, it follows that every Word must denote things only as related to the other factors of the Injunction, and no word can be comprehended as having any denotation when taken apart from such Sentence. Says Prabhākara (Bṛhatī, p. 135)—‘What is eternal is the Relation which the Sentence bears to what it expresses,’—on which the Ṛjuvimālā remarks—The Word, alone by itself, never expresses any meaning; it is only the Sentence that does it; as is clear from the fact that we learn the meaning of Verbal expressions only from the usage of older people,—and this usage is only in the form of Sentences; and every single Word is understood only in so far as it is related to the other words in the Sentence; hence it becomes established that what is expressive of the meaning is the Sentence only, not any Word alone by itself.—(Ṛjuvimālā, p. 135.)