If you have ever lain awake at 3 a.m. running through a conversation you cannot rewrite, a decision someone else has already made, or a future event you cannot guarantee, you have arrived at the specific psychological territory that a former Roman slave named Epictetus mapped out approximately 1,900 years before you got there. Epictetus, who lived from roughly 50 to 135 CE, did not write anything down. His teachings were recorded by his student Arrian, who transcribed his lectures and later compiled the most essential ones into a short handbook called the Enchiridion. The handbook, approximately 53 short chapters long, opens with what is probably the single most consequential sentence in the entire Stoic tradition. According to the Stanford Encyclopedia of Philosophy’s entry on Epictetus, the line begins: “Of things that exist, some are in our power and some are not in our power. Those that are in our power are conception, choice, desire, aversion, and in a word, those things that are our own doing. Those that are not under our control are the body, property or possessions, reputation, positions of authority, and in a word, such things that are not our own doing.”
What Epictetus then argued is that almost all human suffering arises from a single, repeated, correctable error: confusing the first category with the second. We try to control things that belong in the not-in-our-power column — other people’s opinions of us, the behaviour of relatives, the outcome of negotiations, the weather, the economy, the past, the future, our own bodies and lifespans — and we neglect the small, genuinely controllable category, which consists of our own judgements, intentions, and responses. The result is chronic frustration about things we were never going to be able to change, accompanied by chronic neglect of the things we actually could change. The Stoic prescription, articulated in chapter 1 of the Enchiridion and elaborated across the much longer Discourses, is to perform this sorting deliberately and continuously, until it becomes second nature.
The dichotomy in practice
The classical Stoic exercises around what modern Stoic-revival writers have called the “dichotomy of control” were not abstract philosophical contemplations. They were daily practices, intended to be performed in the morning before the rest of the day’s events began, and reviewed in the evening after the day was over. The morning practice involved anticipating the day’s likely difficulties — encounters with rude or dishonest people, unexpected setbacks, frustrations of various kinds — and pre-sorting them into the two categories. The encounter with the rude colleague would happen or not happen; that was not in our control. Our response to it was. The traffic on the road would be heavy or light; that was not in our control. Our patience inside that traffic was. The clients we hoped to sign would sign or not sign; that was not in our control. Our preparation, our presentation, and our equanimity in the meeting were.
The same logic applied to the bigger questions of a life. Whether one’s children turn out as one hopes, whether one is loved by the people one loves, whether one’s career succeeds, whether one stays healthy, whether one lives to be old — Epictetus would have placed all of these squarely in the not-in-our-power column. The only things in our power, in his strict reading, are our own judgements and responses. As the modern Stoic writer Donald Robertson summarises the framework, drawing on Epictetus’s own emphasis: maintaining the distinction between what is up to us and what is not is the foundational practice from which all other Stoic exercises follow. Per Philosophy Break’s reference on the dichotomy of control as a Stoic device for a tranquil mind, the point of the practice was not resignation but reallocation of attention — moving one’s effort away from the controllable shape of the world and toward the controllable shape of one’s own response to whatever world arrives.
The route from Greece to the modern clinic
The connection between Epictetus’s teaching and modern cognitive behavioural therapy is not a strained academic parallel. It is direct, documented, and explicitly acknowledged by the founders of the therapeutic tradition themselves. As reported in a 2023 review in Neurological Sciences on the Western origins of mindfulness therapy in ancient Rome, Albert Ellis, the founder of Rational Emotive Behavior Therapy in 1955, explicitly credited Epictetus as the primary philosophical influence on his approach. Ellis quoted the famous line from chapter 5 of the Enchiridion — “Men are disturbed not by things, but by the views which they take of them” — in his foundational 1955 paper introducing the new therapeutic method, and reproduced it in numerous subsequent publications. Aaron Beck, who developed Cognitive Therapy in the 1960s (the broader framework that came to be called Cognitive Behavioural Therapy when combined with behavioural techniques), wrote in his original treatment manual for depression that “the philosophical origins of cognitive therapy can be traced back to the Stoic philosophers, particularly Epictetus.”
The structural parallels are precise. Ellis’s foundational ABC model — Activating event, Belief about the event, Consequence (emotional or behavioural) — maps almost exactly onto Epictetus’s distinction between events themselves and our judgements about events. The CBT technique of “cognitive restructuring,” which involves identifying automatic negative thoughts and examining whether they accurately reflect reality, is structurally identical to the Stoic exercise of examining one’s judgements about external events. The CBT concept of “locus of control” — directing attention toward what one can influence rather than what one cannot — is the dichotomy of control restated in the language of mid-twentieth-century psychology. Even the third-wave therapies like Acceptance and Commitment Therapy (ACT) and Dialectical Behavior Therapy (DBT), which add components of mindfulness and acceptance, draw on Stoic exercises that Ellis and Beck had originally underemphasised. The Serenity Prayer, written by Reinhold Niebuhr in 1932 — “grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference” — is the dichotomy of control rendered in twentieth-century devotional language.
What the evidence base now shows
The descendant of Epictetus’s teaching is now, by a substantial margin, the most empirically supported form of psychotherapy in modern medicine. Cognitive Behavioural Therapy has been tested in literally thousands of randomised controlled trials across the past five decades, covering depression, generalised anxiety disorder, panic disorder, post-traumatic stress disorder, obsessive-compulsive disorder, eating disorders, insomnia, chronic pain, and a long list of other conditions. The aggregate effect sizes from meta-analyses are typically in the moderate to large range, with Cohen’s d values between approximately 0.5 and 1.0 depending on the condition and the specific protocol. CBT is the first-line recommended treatment for several major mental-health conditions in clinical guidelines issued by the National Institute for Health and Care Excellence in the UK, the American Psychiatric Association, the American Psychological Association, and equivalent bodies across most developed countries.
As documented in the Robertson and Codd 2019 paper in The Behavior Therapist, the central therapeutic insight that runs through this entire empirical edifice — that emotional disturbance is mediated by judgements about events rather than by the events themselves, and that the path to reduced disturbance runs through revising the judgements rather than changing the events — is, in essentially its original form, what Epictetus was teaching his students in Nicopolis in the late first and early second centuries CE. The mechanism is the same. The vocabulary has changed. The clinical context has changed. The empirical infrastructure has changed beyond anything anyone in ancient Rome could have imagined. But the basic move at the heart of the intervention — sorting the things that are up to us from the things that are not, and reallocating attention accordingly — is recognisably the same move that opens chapter 1 of the Enchiridion.
What the framework asks
The practical implication for an ordinary person not currently in therapy is not that they should adopt the entire apparatus of clinical CBT. It is that the basic distinction Epictetus drew is available to anyone, costs nothing, and has been validated by approximately seventy years of clinical research and approximately two thousand years of philosophical practice. The exercise itself is straightforward. Whatever is currently troubling you — the conversation, the decision, the rejection, the diagnosis, the news, the relative, the political situation, the future you cannot guarantee — has two components. Some part of it is genuinely within your power to change. Some part of it is not. Sorting the two takes a few minutes of honest attention. Most of the suffering, in Epictetus’s account, comes from skipping that step. Most of the relief, in the modern CBT literature, comes from doing it.
