This article is part of a series of modified excerpts from the introduction to our book "On Virtue." 

Article 2 - Know Yourself

At least 2,800 years ago there was an oracle in Delphi, Greece. Men and women went to the Oracle of Delphi to ask advice on important problems in life. Kings asked the oracle how to make wise laws and slaves asked how to break them. Old generals asked her how to win wars and young people asked how to find love. Everybody asked her about the problems that made them suffer.

For centuries, the Oracle of Delphi earned a reputation for helping individuals solve problems in their life that they could not solve themselves. Some claimed the oracle could even foretell the future, because the advice she gave was so wise. The most amazing thing about the oracle’s advice was that, in addition to the individualized advice she gave, there was one piece of advice she gave to everybody. This piece of advice was so important that it was engraved in stone.

Each person who walked up to the oracle would notice before them an engraving, “Know Thyself.”

At first, it seems simple to know yourself. You might even think, “How could I not know myself?” However, as you mature and continue learning new things, it is easy to understand what the oracle meant. Only then does it become clear why knowing yourself is the key to unlocking your happiness in life.

Zeno of Citium founded the Stoic School. He taught that the most important thing to know about yourself is that everything in your life will be either something you can control or something you cannot control. From that observation, he discovered the key to happiness is accepting what you cannot control.

For example, diseases, your age, the actions of others, and what others think about you are things you cannot control. Nature limits everybody. Therefore, trying to control these things amounts to trying to control nature. Zeno called trying to control nature “hubris.” He taught that hubris only brings anxiety, depression, frustration and other negative emotions. He taught that one key to a happy life is knowing yourself well enough to know that you can direct your emotions away from the things you cannot control and can experience peaceful emotions by focusing on what you can control.

The next article discusses another part of knowing yourself. Learning what is in your control will help you build more happiness and better friendships.