Who do you think Charlie is writing to?

Most people believe that Charlie is writing to himself. I have always believed that he was writing to an "ideal", someone he believed would listen if given the opportunity to share his thoughts. The person might not be real..... but that didn't matter. Writing and recording was the purpose.

Note, there are others who cite the following passage as explain the "girl" Charlie was writing to..... in context, I think she is his "ideal" (already stated), but since we're never told for sure.... they might be right.

"I just don't want you to think that I picked your name out of the phone book. It would kill me if you thought that. So, please believe me when I tell you that I felt terrible after Michael died, and I saw a girl in class, who didn't notice me, and she talked all about you to a friend of hers. And even though I didn't know you, I felt like I did because you sounded like such a good person. The kind of person who wouldn't mind receiving letters from a kid. The kind of person who would understand how they were better than a diary because there is communion and a diary can be found."