Synopsis
The famous stoic philosopher Epictetus lived as a slave and then as a free man in Ancient Rome. He is one of the more important stoics. He said that the only thing we can control is our thoughts as they are internal. We cannot control the external world.
A great question to ask to ourselves is based on the dichotomy of control. What things are within our control and that things are without our control. The answers are valuable to our personal development.