The Ladies' Book of Etiquette, and Manual of Politeness

Avoid always any discussion upon religious topics, unless you are perfectly certain that your remarks cannot annoy or pain any one present. If you are tete-a-tete with a friend, and such a discussion arise, inquire your companion's church and mention your own, that you may yourself avoid unpleasant remarks, and caution him. Never, when advancing an opinion, assert positively that a thing "is so," but give your opinion as an opinion. Say, "I think this is so," or "these are my views," but remember that your companion may be better informed upon the subject under discussion, or, where it is a mere matter of taste or feeling, do not expect that all the world will feel exactly as you do. Never repeat to a person with whom you converse, any unpleasant speech you may have heard concerning her. If you can give her pleasure by the repetition of a delicate compliment, or token of approval shown by a mutual friend, tell her the pleasant speech or incident, but do not hurt her feelings, or involve her in a quarrel by the repetition of ill-natured remarks. Amongst well-bred persons, every conversation is considered in a measure confidential. A lady or gentleman tacitly confides in you when he (or she) tells you an incident which may cause trouble if repeated, and you violate a confidence as much in such a repetition, as if you were bound over to secrecy. Remember this. Never criticise a companion's dress, or indeed make any remark whatever upon it. If a near friend, you may, if sincere, admire any article, but with a mere acquaintance let it pass unnoticed. If, however, any accident has happened to the dress, of which she is ignorant, tell her of it, and assist her in repairing the mischief.