A long time ago, an exceptionally charming, intelligent young man travelled from a tiny village in the Peloponnese to Athens, with the intention to learn wisdom from one of the many wise men there who taught philosophy.
After he had listened to several of the famous teachers in the Agora, he felt that he could in fact not learn much from them, and decided instead to try to speak to Diogenes. However, when he asked people the way to Diogenes, they tried to strongly dissuade him from that idea.
“Why do you speak so negatively about Diogenes?” the young man asked them.
“Because he is deserving of it,” they answered.
The young man was intrigued and went to Diogenes.
“What can I do for you, my friend?” Diogenes asked the young man.
“I have come to speak with you, Diogenes, and to learn from you if you are willing to teach me.”
“I see. You wish to receive a good education. That is admirable: you are a conscientious young man.”
“Why do you think I am conscientious?” the young man asked.
“You would like your country to have a good foundation, and the education of youth is the best foundation of all,” Diogenes answered.
“What can you teach me?”
“I can teach you one single thing, and that would be to realize that you do not know anything. But remember that it takes much time and effort to achieve that insight,” replied Diogenes.
“But I already feel that I do not know anything,” the young man said.
“That feeling you have now must ripen. Only after you have learnt much and still feel that you do not know anything, only then will you understand this most important point.”
“What is the greatest virtue?”
“There is only one: it is the ability to ask yourself if how you treat others is correct or not, and to act accordingly.”
“But how can I know for sure that the answer I hear in my head is the right one?”
“That is very simple: do not do to others what you would not like them to do to you.”
“I have heard it said that you say you are not a real Athenian, is that true?”
“They do not understand what I mean. I am a cosmopolitan, a citizen of the universe; but because all the celestial bodies including the Earth on which we live are in the cosmos, I am also a citizen of the Earth, a true global citizen. Finally, because Greece and Athens are parts of the Earth, I am also a citizen of Athens. Those who feel that they are only citizens of Athens, on the other hand, are as apes in a cage.”
“How is it possible that they do not notice that they are in a cage?”
“Just think a little: people standing in front of the cage see the apes through the bars and think that the apes are behind bars; the apes see the people through the bars and also have the impression that the people are behind bars. Therefore people watching monkeys in a cage are, in effect, looking at themselves in a mirror.”