Stoicism has never fully disappeared — it's been an open secret passed person-to-person among the powerful for centuries. The Enlightenment thinkers, the American Founding Fathers, Civil War generals, and Vietnam POWs all turned to it. It resurges in turbulent times because when the world feels out of control, the most useful question is: what can I control about myself? The Stoics wrote the smartest answer to that question ever written.