I'm thinking specifically about anecdotes like this. http://www.avani-mehta.com/2008/08/08/how-fart-can-make-you-grow-spiritually-su-dongpos-story/ Events like these, which don't shape the way a society functions by themselves, but are light-hearted situations that happened in a person's life that might explain some of the decisions the person makes later. They often sound like somebody made them up, or at least changed some of the details to make for a better anecdote, the same way that someone writing a biography or autobiography about a famous person today might change some of the details of an event in their life to make the book itself more streamlined/entertaining/etc. We know that a man named Su Shi/Su Dongpo existed in 11th century China, but how do we know that this event actually happened to this man?

I'm reminded of how people sometimes attribute quotes or events to famous people from history, like Albert Einstein, Barack Obama, William Shakespeare, and so on. These people definitely existed, but there are many anecdotes that people attribute to them (eg. "That boy grew up to be Albert Einstein"). Without the help of detailed records of a person's life, like we have now, how do we separate anecdotes like these from the facts of a person's life? How do we know which anecdotes really are facts?