Zenon was the founder of the "Stoa", a philososhy school in the anciant greek. They teached things everyone should know: We can not control anything that happens in the outside. We have to accept it as it is. But what we can control is everything in the inside. Our feelings arise from our thoughts, which we can control, and these feelings in turn lead to our actions, which are thus fully controlled. For example, a slow driver drives in front of you and you can not overtake him. What good is it for you to get upset and rage? He will not drive faster. You only hurt yourself at that moment. Therefore, do not be stupid and control your thoughts, which affect your feelings which result in your actions. That leads to "The stoic serenity." - Have a great day :-)