From Augustine’s On Christian Teaching (4.10-11):
What is the use of correct speech if it does not meet with the listener’s understanding? There is no point in speaking at all if our words are not understood by the people to whose understanding our words are directed. The teacher, then, will avoid all words that do not communicate; if, in their place, he can use other words which are intelligible in their correct forms, he will choose to do that, but if he cannot—either because they do not exist or because they do not occur to him at the time—he will use words that are less correct, provided that the subject-matter itself is communicated and learnt correctly.
This aim of being intelligible should be strenuously pursued . . . . What use is a golden key, if it cannot unlock what we want to be unlocked, and what is wrong with a wooden one, if it can, since our sole aim is to open closed doors?
HT: Jeremy Larson