Only three Roman Stoics survive in quantity, and they wrote in completely different genres: a handbook, a private journal, and a collection of letters. Their reputations do not track their usefulness to a beginner, which is why so many people bounce off Stoicism after starting with the wrong one.
Epictetus was born a slave and taught as a freedman, and his style is correspondingly unsentimental. The Enchiridion — the word means handbook — opens with the doctrine everything else rests on: some things are within our power and some are not. Our judgements, intentions and responses are ours; our bodies, reputations, and circumstances are not. Almost all suffering, on this account, comes from treating the second category as if it belonged to the first. That single distinction is the load-bearing element of the entire philosophy, and Epictetus states it in the first paragraph.
Marcus Aurelius wrote the Meditations for nobody. It has no argument, no structure, and considerable repetition, because he was reminding himself of the same things over and over — which is exactly what makes it moving once you know what he is reminding himself of, and exactly why it confuses people who start there. Read after Epictetus, the repetition reads as a man applying a doctrine under pressure rather than as an author failing to organise his material.
Seneca is the best prose stylist of the three and the most immediately practical, writing to a friend about grief, anger, time, and the fear of death. The letters need no order. He is also the most complicated figure: enormously wealthy, and tutor and adviser to Nero, which has raised charges of hypocrisy since antiquity. Reading him with that tension in view is more interesting than ignoring it, since much of what he writes about the corrupting pull of wealth and power reads differently coming from someone with both.
A cautionWhat popular Stoicism leaves out.
Modern Stoicism is usually presented as a set of psychological techniques — control what you can, reframe adversity, practise negative visualisation. These work, and they are genuinely useful. But they are the practical surface of a complete philosophical system, and the parts most often dropped are load-bearing.
Ancient Stoicism held that virtue is the only good, and that health, wealth and reputation are strictly indifferent — preferable, but with no bearing on whether your life goes well. It also rested on a physics: the universe is a rational, providentially ordered whole, and accepting what happens makes sense because what happens is the working of that order. Detach the techniques from those commitments and you get a stress-management method rather than an ethics — which may be what someone wants, but it is worth knowing the substitution has been made.
The most common misreading is that Stoicism means suppressing emotion. It does not. The Stoic claim is that emotions follow from judgements, so the work is done at the level of what you believe about a situation, not by clenching against a feeling you already have. A Stoic who has genuinely stopped believing that reputation matters does not have to suppress anything.