George Washington's Rules of Civility Traced to their Sources and Restored by Moncure D. Conway
Chapter vii. 11. Ne vous seruez iamais en vos discours & n'employez
vne langue qui ne vous est pas bien cognuë & familiere, si ce n'est en vne occasion bien pressante, pour donner plus clairement à connoistre vostre pensée. Parlez tousiours en la vostre maternelle & natale, non pas grossierement, comme la lie du peuple, ou les pauures chambrieres; mais comme les plus delicats & les plus gros Bourgeois, auec erudition & auec elegance. Et prenez à tâche d'obseruer en vos discours les regles de l'honnesteté & de la modestie; & vous gardez bien de ces contes vn peu trop libres; ne les faites ny en l'oreille d'vn autre, ny ne les poussez par jeu auec profusion. N'employez point de termes bas & raualez ou populaires en des matieres hautes & reluées.
In your conversation never use a language with which you are not thoroughly acquainted and familiar, unless in some very urgent case to render your idea more clearly. Always speak in your native and mother tongue, not coarsely like the dregs of the people, or poor chamber-maids, but like the most refined and well-to-do citizens, with erudition and elegance. And in your discourse take care to observe the rules of decorum and modesty, and be sure to avoid rather risky tales; do not whisper such to another, and do not indulge them too frequently in sport. Do not use low, base or vulgar expressions when treating of serious and sublime subjects.
73'd. Think before you Speak pronounce not imperfectly nor bring out your Words too hastily but orderly and Distinctly