It was an additional act of revenge.
They are probably the most important document in understanding history. Without writing we would have a difficult time understanding archeological data. Also journals give great detail about wars and other major conflicts that would otherwise be unknown to historians.
All of these could be considered an "author's purpose". An author is technically anyone who writes anything, therefore the purpose of writing is theoretically limitless. If you have to choose one of these, however, it would be "to remind".
Huh ?? But I don’t know to be completely honest.
