Just and juster

Once a year the Athenians would meet and vote on exiling someone. If a simple majority voted yes, then they dispersed and reassembled two months later. They brought with them their ostracon (a fragment of pottery), on which they had scratched the name of the person they thought represented a threat. The man with the most votes lost. He was exiled for 10 years, They not only voted people into office, but they had a regular procedure for voting one person per year out of office. It was an option which could be exercised but did not have to be. The exile did not involve confiscation or any other punitive measures.

Aristides was known for his probity, and often called Aristides the Just.  On one occasion, a voter, who did not know him, came up to him, and giving him his shard, asked him to write upon it the name of Aristides. The latter asked if Aristides had wronged him. “No,” was the reply, “and I do not even know him, but it irritates me to hear him everywhere called the just.”

There's a moral to this story, but I don't know what it is.