Stoicism is having a moment. It’s always been popular in certain circles, for example as a buttress against chaos for military men. U.S. Admiral James Stockdale famously used the Stoic counsel of the ancient sage Epictetus to steady his mind as a prisoner of war in Vietnam. But recently Stoicism has gone mainstream in less dramatic scenarios as well. It’s a major source of inspiration for Cognitive Behavioral Therapy (CBT), an appealingly sensible form of professional counseling that eschews Freudian navel-gazing in favor of actionable mental discipline. In the 2010s, marquee titles like Ryan Holiday’s The Obstacle Is the Way (2014), named after a famous aphorism from Emperor Marcus Aurelius’ Meditations, helped establish a cottage industry of influencers who offer digestible neo-Stoic rules for life. Donald J. Robertson, a cognitive behavioral therapist and a well-respected popularizer of Stoic teaching, is part of this trend. His new biography, Marcus Aurelius: The Stoic Emperor, is a readable introduction to the ancient world’s most celebrated philosopher-king.

Stoicism’s most effective ideas are timeless: focus on what you can change, accept what you can’t. Cultivate a habit of thinking through your emotions before acting on them. These kinds of practices have always enjoyed some degree of popular appeal, ever since they were