I pray you, my good young friend, that you will not discourse of things other than business in your letters. It will doubtless please your friends to know that you are well, and that you look forward to getting home to them. Is it not so?

– Bram Stoker

Dracula, Chapter 3. Count Dracula to Jonathan Harker, whom he is holding prisoner. There is a sense of menace in the advice here that Jonathan is not to discuss anything other than business in the letters the Count is dictating to him to write.