In life, two things are for certain. Death, and taxes.

Nathaniel Hawthorne made the introduction to the Scarlet Letter to prove to the readers that it was true. He wanted to write a story that people would think was real, instead of writing a non-fictional story. I think it was a God complex, to be honest. Instead of just saying, "Kay, guys, here's a story that I wrote about not ostracize your neighbors," it was, "Here's this DOCUMENTED proof that Hester Prynne existed, and here are the hard-ships that she and her illegitimate child Pearl went through."