3. Never interrupt anyone who is speaking; it is quite rude to officiously supply a name or date about which another hesitates, unless you are asked to do so. Another gross breach of etiquette is to anticipate the point of a story which another person is reciting, or to take it from his lips to finish it in your own language. Some persons plead as an excuse for this breach of etiquette, that the reciter was spoiling a good story by a bad manner, but this does not mend the matter. It is surely rude to give a man to understand that you do not consider him capable of finishing an anecdote that he has commenced.
I need to be better about this rule.
2. Retain, if you will, a fixed political opinion, yet do not parade it upon all occasions, and, above all, do not endeavor to force others to agree with you. Listen calmly to their ideas upon the same subjects, and if you cannot agree, differ politely, and while your opponent may set you down as a bad politician, let him be obliged to admit that you are a gentleman.