Secret diaries encourage the worst and darkest sorts of thoughts a person has. Secret diaries are often filled with complaints, insults, and grievances with others. Why? A secret diary needs a reason to be secret, which means you will fill it with the sorts of thoughts you don’t want other people hearing, which either means confessing your own sins or the sins of others. A diary is no place to confess your sins, though, because a diary can’t forgive you. And it’s no place to catalogue the sins of others … Writing things down formalizes them, confirms them, solidifies them. Writing down your thoughts takes time, and so you linger over all the unsavory thoughts you don’t want others to hear. It is one thing to have those thoughts, but another thing to dwell on them. If you have a mean or nasty thought about someone, there’s no need to make them permanent by recording them and coming back to them later.

He also affirms what a diary is good for.

This should remind me to be more serious about a good diary.