The so-called “Big Three“ Roman Stoics wrote some incredibly powerful and influential literature. Seneca, Epictetus, and of course the emperor-philosopher Marcus Aurelius are by far the most popular authors among fans of Stoicism today, and modern Stoic practice would scarcely be possible without them!
But for all their hard-hitting advice and thematic consistency, the Big Three can sometimes be a frustratingly limited resource. As remarkable as they are for their artfully crafted window into Stoic practice, these texts were not meant for beginners. None of them really attempt to offer a survey or general explanation of the Stoic life and its aspirations: modern readers of these texts are just kind of left to pick it up as they go along. Because of this, the provocative ideas that are found in the Big Three often raise as many questions for modern readers as they answer. The big ideas that pull Stoicism together into a coherent and compelling philosophy of life tend to be hidden in the background, where they are only alluded to in a brief and piecemeal fashion.
Luckily, there is quite a bit more literature by and about Stoics that survives from the ancient world! This additional material is essential for anyone who is trying to really understand (much less live by) the moral and mindful life recommended by these ancient philosophers:
Let’s take a look at some of the highlights of this extended Stoic corpus.
1. The Lectures of Musonius Rufus
Musonius Rufus—a philosopher renowned in his day as the so-called “Roman Socrates“—was Epictetus’s teacher in Rome. He was known for the way that his rousing ethical lectures could leave an audience stunned silent, slicing through people’s defensive justifications and inspiring them to recognize their own distance from the philosophical ideal. He was clearly a man who made an impression on his students, and Epictetus refers to him often.
Some of this “stunning” quality is captured in a handful of transcribed Lectures that survive from Rufus’s teaching career. The entire collection is smaller than the Meditations and barely a third of the length of the surviving Discourses, but it packs a punch. His arguments tend to be clear and straightforward to follow, and the topics covered by each of the Lectures touch on some of the most provocative and socially important themes of ancient Stoic literature: cosmopolitanism and public service, the equality of women, the interplay between theory and practice in the philosophical life, sexuality, and—in a practice that Rufus is especially keen on—the exercise of dietary temperance!
Rufus has been variously called a proto-feminist and the West’s first ascetic theorist, and while I don’t agree with him on everything, what I find especially valuable is his laser-sharp focus on the four virtues and social engagement as guides to the Stoic life. This moral emphasis is something that he shares with earlier Greek Stoics, and it stands in sharp contrast to Epictetus, who rarely mentions virtue and prefers to focus a bit more narrowly on emotional equanimity.
The Lectures are less widely known than the works of Seneca, Epictetus, and Marcus, but Musonius Rufus shares their preoccupation with practice and their sharp instructional tone. He absolutely deserves to be recognized alongside them as one of the core authors of the superb practice-oriented literature that came out of Roman Stoicism—so, the “Big Four.”
2. The Hymn to Zeus by Cleanthes, and other early fragments
It’s certainly convenient when complete (or nearly complete) books survive, as with the Big Four. And it’s true that relatively little of the Early and Middle Stoa’s literature is extant today. What does survive is scattered in quotes (“fragments”) and summaries (“testimonia”) that appear throughout the works of Cicero, Diogenes Laertius, Sextus Empiricus, Plutarch, Galen, Aulus Gellius, Augustine of Hippo, and other secondary sources.
But don’t let their small combined page count fool you, and don’t underestimate the value of fragments and testimonies! These are highly concentrated summaries of the parts of Stoic philosophy that later authors felt the most compelled to refer to for centuries to come. These numerous nuggets transmit a lot of important ideas from Zeno, Cleanthes, Chrysippus, Aristo, Posidonius, Panaetius, and other major Stoic teachers—and they arguably tell us much more about the structure of their philosophy and ethical world view than all of the Big Four combined.
By far the earliest surviving piece of extended Stoic literature, and one of my favorites, is the Hymn to Zeus—a famous poem by Cleanthes (the second head of the early Stoa). The poem is often quoted by later authors like Epictetus, and a large portion of its full text has survived. The Hymn‘s polytheistic background may sound a bit off-putting to our modern sensibilities at first, but if you have any familiarity with contemporary Traditional Stoicism—with its interpretation of Stoic theology as a kind of timeless, “rational spirituality“—then the Hymn still has power to speak to us in significant ways today.
Another treasure that emerges from the early Stoic fragments—though I’m showing my technical chalk as a computer scientist here—is a description of their intricate system of logic. The Stoics pioneered a remarkably modern-seeming system of propositional logic, and distant descendants of their system are still taught in college classrooms today. Thanks to Diogenes Laertius, a big chunk of an ancient logic textbook has come down to us that preserves the rules and assumptions of this Stoic system of logic.
As to the rest, there is a hard way and an easy way to approach the scattered Early- and Middle-Stoic remnants:
- The easy way is to let somebody else do the work of tracking down all the fragments for you. AFAIK, Inwood and Gershon’s Stoics Reader is the best such resource that exists in English. This is a fantastic way to familiarize yourself with bits of Stoic logic, ethics, and physics without taking the time to comb through, you know, all of ancient Greek literature to find relevant fragments!
- The hard way, meanwhile, is to read them in the full context of the major secondary sources that have preserved them, like Diogenes Laertius’ Lives of the Eminent Philosophers. The authors of these surviving texts often situate Stoic ideas within larger discussions of what matters for human life, and alongside competing ideas from other ancients schools.
As a practicing modern Stoic, I have found it especially worthwhile to approach Cicero’s work as whole, rather than jumping from Stoic testimony to Stoic testimony. Much of Cicero’s work reads as a concise and well-argued textbook of Stoic ethics—offering crucial context and arguments for Stoicism that go into far more detail than any of the Big Four.
With that in mind, let’s turn next to two highlights from Cicero’s voluminous corpus.
3. On Ends by Cicero
This remarkable dialogue is probably the single most eye-opening source you can read if you want to really understand Stoic ethics. Cicero—arguably the most famous figure in all of Latin literature—was not a Stoic himself (he was proud of his independence as an Academic Skeptic), but he did agree with essentially all of Stoic ethics. Most of his surviving philosophical works effectively served as introductory textbooks that survey Greek Stoic doctrines for his Latin-speaking audience.
Cicero’s work belongs to an entirely different genre than the Big Four. His stated aim in much of his work is to try and give a fair explanation of what each of the major schools of Greco-Roman philosophy believe and why they find it compelling, getting as close as possible to showing you the best ways that real flesh-and-blood followers of various philosophies would explain their world view and defend it against critics. His biases do show—he was notoriously hard on the Epicureans, for example—but his treatment of Stoicism is typically very sympathetic.
On Ends (widely known by its Latin title, De Finibus) is Cicero’s introduction to Hellenistic ethics, and it is one of our most important surviving sources for details of Stoic ethical thought in particular. Many powerful ideas that contemporary Stoics hold to close to their hearts are Greek concepts that have been preserved primarily in Cicero’s Latin—such as the Stoic developmental theory of ethical naturalism (oikeiosis), the metaphor of the Archer, and even an early version of the Circles of Hierocles (a Stoic form of compassion meditation).
Now, for me, Cicero’s dialogues are no substitute for the Big Four in terms of their usefulness for daily practice. Epictetus and the rest are willing to get down in the trenches with me, so to speak, and help me wrestle with the moment-to-moment dirty work of mindfulness and moral discipline. But at the same time, Cicero’s more cerebral extended arguments have probably done more than any other ancient author to help me clarify my own understanding of the Stoic life and the reasons that I find it a worthwhile and compelling path to follow. As with Rufus, I don’t agree with everything he says, but his work does a fantastic job of bringing the major core components of the Stoic value system into the foreground.
4. Tusculan Disputations by Cicero
The Tusculan Disputations is your one-stop shop for everything about the Stoic theory of emotions and psychotherapy. In between an opening detour into Platonic speculations about death and a closing book defending the Stoic doctrine that “virtue is the only good,” Cicero’s dialogue characters systematically step through Stoic views on several broad emotional themes—like methods for enduring pain and managing distress.
This is where you will learn that, far from rejecting all emotions, the Stoics in fact divided emotions into three kinds—unhealthy passions, proto-passions, and healthy passions—and that the philosophy actively encourages certain kinds of intense emotions (even negative ones!).
Along the way, and among other things, Cicero leads us along lengthy discussions of the Stoic view of anger, and of how the ancient Greco-Roman exercise of negative visualization (praemeditatio malorum) is supposed to help us better manage our emotions during trying times.
5. On the Heavens by Cleomedes
A well-kept secret is that, in addition to the Big Four, there was actually a fifth Roman-era Stoic for whom a complete work survives! It’s Cleomedes, with his astronomy text, On the Circular Motions of the Celestial Bodies (or simply, On the Heavens).
Of course, this book treats natural science, not so much ethics, so it’s not going to offer the same sort of wildly practical insights as the Big Four and Cicero. But as with Seneca’s Natural Questions, bits of Stoic philosophy feature here and there throughout the book.