To the Stoics, though, the crucial limits to freedom are internal, not external. Many people who are free outwardly are enslaved by the contents of their own minds. We become free, Zeno proposed, if we recognize the difference between the things we control and the things we don’t. What do we control? Our actions in our outer lives—our words and deeds—and our actions in our inner lives—our thoughts, beliefs, and values. What don’t we control? Everything else.
To the Stoic, then, the things you control are the things that matter. The process of becoming a Stoic is one of learning how to value the things you control more than the things you don’t control.