Epictetus, the Markov Blanket, and the Art of Clean Boundaries
“Some things are in our control and others not.”
Epictetus wrote that nearly two thousand years ago. Born a slave in the Roman Empire, he knew this boundary not as theory but as survival. His body, labour, even movement belonged to others—yet he insisted that freedom remained: not in events, but in how he chose to respond.
That single insight—the line between what we govern and what we cannot—is the Stoic gateway to real power: the ability to focus every ounce of energy where it actually changes the world.
See the line. Act inside it. Release the rest.
A Modern Echo: The Markov Blanket
Neuroscience draws the same line in different ink.
Every living system survives within an information boundary—what researchers call a Markov blanket.
Inside are the states it can directly influence.
Outside lies the environment it can only sense.
Across the boundary flow signals: sensations in, actions out.
This constraint is what allows complex systems and living organisms to remain coherent—free to adapt without falling apart.
The Engineer’s Rule: Separation of Concerns
Modern engineers see the same principle in code design.
Each module focuses on its own task and communicates through clear interfaces.
Human life follows the same pattern:
Inside concern: attention, interpretation, choice, action.
Outside concern: other people’s decisions, the economy, tomorrow’s weather.
Blur those lines and anxiety follows—just like bugs in tangled code.
Two Predictable Failure Modes
Ignore the line and two things happen:
Stress & wasted energy – chasing what you can’t control.
Shrinking agency – underestimating how much is within reach.
Hold the line and the reverse unfolds:
⚡ Energy concentrates where it counts.
⚡ Agency expands as focused action reshapes what’s inside.
Living the Line
This isn’t about staying small.
The boundary is a living edge: clear enough to steady us, flexible enough to grow.
Humans are unique: our boundary isn’t fixed.
We can learn, build skills, and form relationships that pull more of the world inside our sphere of influence.
Notice where your influence is real and where it isn’t.
Act where change is possible, and let the rest move past.
At that edge, there is room to test yourself.
Stretch for what may be within reach.
The line often widens only when we press against it.
Freedom begins when we accept the line.
Impact multiplies when we work fiercely inside it—because every action there lands with full force.
Pause and claim the space that’s already yours—and feel the momentum that comes when every action is aimed where it matters most.
