"What a man cannot state, he does not perfectly know, and conversely, the inability to put his thoughts into words sets a boundary to his thought . . . . English is not merely the medium of our thought: it is the very stuff and process of it."
Report of the Departmental Committee on the Teaching of English in England (1921) (as quoted in Sir Ernest Gowers, The Complete Plain Words 14 (1954; repr. 1964)).