A man's character is the direct result of his understanding, which itself is the use of language. So inevitably a man reveals the nature of his character, which is the nature of his understanding, by his use of language. The choice and use of the words employed to communicate must reflect his personality, which is why the Ancient Greeks and Romans made the art of rhetoric the heart of their education system.
Anyone wishing to see a simple demonstration of this effect has just to visit a public speaking group such as 'Toastmasters'. The public speeches not only reveal the speakerʼs ability at oratory but their personality and grasp of reality. (see also the example of a 1980s executive christened Bondi) and just as surely as a man reveals his nature by speaking, or writing, so does society reveal its nature (communal understanding) by the popular expressions of the time; which means diagnosis of communal decline can be done through examination of the common use of words.