46. Surliness or moroseness is incompatible also with politeness. Such as, should any one say "he was desired to present Mr. such-a-one's respects to you," to reply, "What the devil have I to do with his respects?"--"My Lord enquired after you lately, and asked how you did," to answer, "if he wishes to know, let him come and feel my pulse," and the like. A good deal of this often is affected; but whether affected or natural, it is always offensive. A man of this stamp will occasionally be laughed at as an oddity; but in the end will be despised.
47. I should suppose it unnecessary to advise you to adapt your conversation to the company you are in. You would not surely start the same subject, and discourse of it in the same manner, with the old and with the young, with an officer, a clergyman, a philosopher, and a woman? no; your good sense will undoubtedly teach you to be serious with the serious, gay with the gay, and to trifle with the triflers.
48. There are certain expressions which are exceedingly rude, and yet there are people of liberal education that sometimes use them; as, "You don't understand me, sir." "Is it not so?" "You mistake." "You know nothing of the matter," &c. Is it not better to say, "I believe I do not express myself so as to be understood." "Let us consider it again, whether we take it right or not." It is much more polite and amiable to make some excuse for another, even in cases where he might justly be blamed, and to represent the mistake as common to both, rather than charge him with insensibility or incomprehension.
49. If any one should have promised you any thing, and not have fulfilled that promise, it would be very impolite to tell him he has forfeited his word; or if the same person should have disappointed you, upon any occasion, would it not be better to say, "You were probably so much engaged, that you forgot my affair;" or, "perhaps it slipped your memory;" rather than, "you thought no more about it:" or, "you pay very little regard to your word." For expressions of this kind leave a sting behind them--They are a kind of provocation and affront, and very often bring on lasting quarrels.
50. Be careful not to appear dark and mysterious, lest you should be thought suspicious; than which, there cannot be a more unamiable character. If you appear mysterious and reserved, others will be truly so with you: and in this case, there is an end to improvement, for you will gather no information. Be reserved, but never seem so.