When you can assume that your audience holds the same beliefs you do, you can relax and use more normal means of talking to it; when you have to assume that it does not, then you have to make your vision apparent by shock — to the hard of hearing you shout, and for the almost-blind you draw large and startling figures.

Mystery and Manners: Occasional Prose (ed. Macmillan, 1969) - ISBN: 9781466829046