§4. Imagine a script in which the letters were used to stand for sounds, and also as signs of emphasis and punctuation. (A script can be conceived as a language for describing sound-patterns.) Now imagine someone interpreting that script as if there were simply a correspondence of letters to sounds and as if the letters had not also completely different functions. Augustine's conception of language is like such an over-simple conception of the script.
It is believed that it was W.'s friend Sraffa, in Cambridge, who stimulated him to the appreciation that language does all sorts of things that are not just naming - in opposition to what seemed to be implied by his Tractatus. Supposedly he challenged W. to explain how his picture theory of how language associated with the world could account for what is communicated by a shrug.
But surely no-one could possibly ever believe that language does no more than name things? Surely Augustine would not have claimed this? Surely W. did not believe it? Unless he thought that in the Tractatus he had proved, in opposition to common sense, that this is necessarily actually all that language can do.