A diary with a known reader is a letter
Once a diarist knows a specific person will read the entries, the diary stops being a record and becomes an argument addressed to that person, and every entry is written partly to wound, justify or persuade them. A reader should treat such journals as a two-party correspondence carried on in private form, not as unguarded inner truth. The only place candour can then survive is a second, hidden notebook, and the existence of that hidden notebook is itself evidence of what the visible one was doing.
