Were you to converse with a king, you ought to be as easy and unembarrassed as with your own valet-de chambre; but yet every look,word, and action should imply the utmost respect.... You must wait till you are spoken to; you must receive, not give, the subject of conversation, and you must even take care that the given subject of such conversation do not lead you into any impropriety.
Letters Written by the Earl of Chesterfield to His Son (ed. 1827)