This section of the book is from the "Household Companion: The Home Book Of Etiquette" book.
A correspondence between two persons is simply a conversation reduced to writing. We should write to an absent person as we would speak to the same party if present. To a superior, we ought to be respectful; to a parent, dutiful and affectionate; to a friend, frank and easy; and clear and definite in our expressions to all.
Conciseness is one of the charms of letter-writing. A letter should contain the desired facts, ideas, and feelings; but they ought to be expressed as briefly as perspicuity and elegance will permit.
Lengthened periods are as much out of place in a letter as they would be in conversation, for they tire the reader even more than they would the hearer. When written, their faults are also perceived with much less difficulty than when spoken.
When the party to whom a letter is addressed is uninterested in the subject on which it is written, the writer of it should display a brevity which will attract attention and insure a perusal. No unnecessary ornament should be used, nor, in fact, anything introduced but what is important and bears strongly on the case stated, or the inquiry made.
To an absent friend, on the contrary, a lengthy epistle, well filled with details of passing incidents, is likely to prove welcome and interesting, and one may venture even upon prolixity if sure that his correspondent has a strong interest in the subject, and is likely to desire minute details concerning it.