On campaign at Carnuntum: the soul examined

Book Three is written, like Book Two, on the northern frontier. The exercises are tighter and more inward. Marcus is examining the soul piece by piece. What is mine, what is the body's, what is added by judgment. He works again on the discipline of assent: an impression arrives — "this is bad," "this is unfair," "this is going to ruin everything" — and the Stoic discipline is to inspect the impression before agreeing to it. Most of what we suffer, Marcus reminds himself, is the agreement, not the event.

The book is also full of memento mori, but more personal than Book Two's. Marcus is older now. He thinks of his predecessors — Hadrian, Trajan, the others — and notes that they are gone, with their schemes and their cruelties and the women they loved. The same thing will happen to him. The exercise is not depressing him; it is sharpening him. If everything is going to be carried away by the river of time, why give any of it your full attention except the part that is actually before you now?

The book ends with a direct exhortation. "Do not act as if you had ten thousand years to live. Death is hanging over your head. Get on with it. Be good while it's still possible." Marcus is reminding himself, not us. But the line lands either way.