For those who wish to truly deep-dive, I strongly suggest to skip the "meta books" on Stoicism, and go straight to the original works. There's the Big Three—Seneca, Epictetus, and Marcus Aurelius. Be prepared to invest at least ten months (the longer, the better) of active study to get a decent grounding.

From my experience of reading multiple translations of the Big Three, for someone new to Stoicism, I'd suggest not to start with the popular recommendation of Marcus Aurelius.

Start with Seneca's Letters, then Epictetus (an ex-slave, and a profound influence on Marcus Aurelius), and only then Marcus Aurelius, the Roman Emperor. (To quote the foremost Stoic scholar, A.A. Long: "[...] That an ex-slave actually shaped a Roman Emperor's deepest thoughts is one of the most remarkable testimonies to the power and applicability of Epictetus' words.")

The quality of the English translation matters a lot. Here are my recommendations:

• Seneca: Letters on Ethics — translation by Margaret Graver and A. A. Long. This is the most recent translation, reads extremely well, outstanding notes, and wonderfully typeset. It's translated by the current foremost experts; can't get better than this. I've been reading this for four months. (If this is a tad pricey for you, I've also heard good things about Selected Letters; translated by Elaine Fantham.)

• Epictetus: Encheiridion, and Selections from Discourses, by A.A. Long. This is a short book; the value addition here is the great introduction, and the outstanding glossary. (NB: there is no escaping full Discourses of Epictetus—refer below.)

• Epictetus: Discourses, Fragments and Handbook — translation by Robin Hard, intro by Christopher Gill; Oxford University Press. Spend a good four months immersing yourself in it. Epictetus is full of heavy irony, dark humor, histrionic wit, and sarcasm. Absolutely my favourite.

• Epictetus: A Stoic and Socratic Guide, by A.A. Long. Important Note: To get maximum value out of this, you must have already read at least one translation of Epictetus' full Discourses! This book orients the reader to Epictetus with an extremely valuable context: how not to misinterpret his unqualified faith in "divine providence" (which can grate on our "modern ears"); the influence of Plato and the "Socratic Elenchus" (colloquially known as "Socratic Method"); deep insights into Epictetus' own inimitable style; and a rich bibliography.

• Marcus Aurelius: Meditations. There are at least six translations. I'd suggest to start with the gentler translation by Gregory Hays. If you like it, then you can research other translations. (A.S.L Farquharson spent a lifetime on his translation of the Meditations; it also has commentary. I sometimes consult this edition.)

• The Inner Citadel: The Meditations of Marcus Aurelius, by Pierre Hadot. This needs to be read only after you've read at least one translation of Marcus Aurelius This is a fantastic dissection of Aurelius' work—Hadot studied him for 25 years. Besides fresh translations of the Meditations, it also contains unparalleled summary of Epictetus, and many quotes of Seneca.

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I'll end with one of my favourite Epictetus quotes:

"For sheep, too, don't vomit up their fodder to show the shepherds how much they've eaten, but digest their food inside them, and produce wool and milk on the outside. And so you likewise shouldn't show off your philosophical principles to ordinary people, but rather show them in the actions that result from those principles when they've been properly digested."