This article is based on the intent of a talk I delivered at Stoicon 2017, and written from the perspective of a practitioner rather than of an academic. It is also a personal perspective. Like Georges Clemenceau who said “War is much too serious a matter to be left to the military,” I feel that the Stoic philosophy is too important to be left to academic philosophers.
What Exactly Is Stoicism?
John Cooper, in Pursuits of Wisdom, points out that “In addressing Stoic ethical theory and the Stoic way of life, we face problems or a set of problems…” not generally found in discussing most other philosophies. The set of problems Cooper talks about revolves around the fact that Stoicism is not the work of an authoritative figure or figures whose writings are still accessible. We have the works of Aristotle that define what Aristotle said; we have the works Xenophon and Plato that define what Socrates said; we have the works of Epicurus to help us define Epicureanism.
But Stoicism, founded by Zeno around 300 BCE, was developed over a period of 500 years. During that time it had seven formal heads (scholarchs) and produced many influential Stoic thinkers. However, we are left with only a fraction, probably about 2%, of their writings, practically all of which belong to the later day Roman Stoics. What the Greek Stoics said from Zeno to the last Scholarch we know from the writings of people like the non-Stoic (but ‘sympathetic’) Cicero and (mostly anecdotal) Diogenes Laertius, who was hardly born when the last great Stoic Marcus Aurelius died. Even if we accept these sparse, and not always reliable, secondary sources as a balanced summary of what the ancient Greek Stoics actually said and meant, we find that the scholarchs had disagreements among themselves.
Even when the ancient Stoics were in agreement, many of the terms they used, such as virtue, god, and ethics, don’t mean the same things today. Again, the way they described things might have been innocuous at the time, but may be considered sexist, racist or in other ways inappropriate or outdated by today’s standards. We have no basis for saying that, were the ancient Stoics to live today, they would use the same examples and express the same ideas. This problem is exacerbated because of the long stretch of time during which Stoicism flourished.
We also must consider the concern that not everything that a Stoic said was based on Stoicism. Some of their views could be their own, colored by the time lived and not necessarily a part of Stoicism. But the extent to which their views reflected the times they lived or Stoicism in is hard to determine because they did not live in a single point of time either.
These observations may sound trite but it is easy to overlook them.
If we agree that there is no single authoritative work on Stoicism that is still accessible, that the ancient Stoics did not agree among themselves, that they may have said many things that were not rooted in Stoic philosophy itself, and that their thinking may have been colored by the long and varied times they lived in, we can more freely examine what Stoicism actually is. We don’t have to consider everything that is in Epictetus’ Discourses, Marcus Aurelius’ Meditations or Seneca’s Epistulae Moralis, or the works of Cicero’s De Finibus Bonorum et Malorum as depicting the inviolable tenets of Stoicism. As Seneca says,
Will I not walk in the footsteps of my predecessors? I will indeed use the ancient road — but if I find another route that is more direct and has fewer ups and downs, I will stake out that one. Those who advanced these doctrines before us are not our masters but our guides.
But this begs the question. If there is no authoritative source to refer to, how can we define Stoicism? Stoic minimalism is one approach to this thorny dilemma. It is the exploration of the question of what makes someone a Stoic with minimal assumptions. Because when there is no single authoritative source and no primary sources of different Stoic thinkers, any number of answers is possible. Disagreements far outnumber agreements. So Stoic minimalism asks the more limited question,
What are the fundamental premises with which one has to agree without which one could not be considered a Stoic?
This inverted approach has two advantages. It looks for agreement rather than disagreements among Stoic thinkers and permits the individual thinkers to pick and choose any other part of Stoicism that they find appealing, thus avoiding unnecessary controversies.
Who exactly is a Stoic minimalist?
Metaphorically, a Stoic minimalist is a curious but skeptical onlooker in the ancient agora, walking by the stoa poikile, stopping and listening carefully to the talks by the Stoics, appreciating their importance, and trying to figure out which part of the philosophers’ esoteric talks has any relevance to his (or her) life.
The Stoic minimalist understands (or assumes) that Stoicism is a rational philosophy of life and its purpose is to help anyone live a better life. It is not a religion and, therefore, nothing needs to be taken on faith, although some propositions could be axiomatic. Stoicism is an internally consistent system and no special training in theory outside of its basic framework is necessary to understand and practice its principles. However, the minimalist is less interested in academic distinctions or theoretical arguments that have no bearing on practice. In deciding what to accept, the Stoic minimalist uses following criteria:
- Does this concept have applications in real life?
When a concept has no obvious relevance to one’s life, the minimalist is free to ignore it.
- Is this concept potentially verifiable and widely accepted as a Stoic principle?
When a concept is not potentially verifiable or not generally regarded as essential to Stoicism, the minimalist is free not to accept it.
- Can the concept be interpreted unambiguously?
When the same concept can be interpreted in more than one way, or has multiple explanations, the minimalist feels free to choose the simplest and the most widely applicable one.
- Is the concept’s literal translation the same as its intended meaning?
When there is a difference between ‘word-for-word’ and ‘thought-for-thought’ interpretation of the Stoic principles, the minimalist chooses to accept the ‘thought-for-thought’ interpretation.
A Stoic minimalist has no desire to distort Stoic principles. A Stoic minimalist is not a revisionist and is largely faithful to the teachings of Stoic philosophy and tries not to deviate from them except based on pre-specified criteria.
Are Stoic Physics or Logic relevant to a practitioner?
Orthodox Stoics held that Stoicism consisted of three subject areas:
- Physics How the universe is organized and run.
- Logic How to establish what is true.
- Ethics How best to live our lives.
They also believed Stoic physics and Stoic logic provided the foundation of Stoic ethics. So do many current-day academic philosophers such as Lawrence Becker, arguably the most prominent of contemporary Stoic theorists. But the contrary perspective that Stoic ethics can stand on its own goes back to the days of Zeno, the founder, and was adopted even before then by the Cynics.
Stoic ethics can be understood and practiced without any reference to Stoic physics or metaphysics, just as a high wire artist can perform extremely well without having any knowledge of the principles of physics that makes his act possible. There is no evidence that proficiency in Stoic physics and logic will make one a better Stoic any more than the knowledge of physics would make a high wire artist a better performer. Besides, many concepts of Stoic physics contradict the findings of modern science. It can also be argued that parts of Stoic arguments are fallacious. But none of these has affected the validity of Stoic ethics. Stoic ethics has not changed, or has become less valid, because its physics and logic has turned out to be not entirely correct. Not one bit.
Rejecting Stoic physics and logic as non-essential (or even irrelevant) parts of Stoicism, especially for a practitioner, is not a revolutionary idea either. One of Zeno’s major students, Aristo(n) of Chios , was one of the earliest Stoics to express this view. This is how Diogenes Laertius describes Aristo’s views:
[Ariston of Chios] wished to discard both Logic and Physics, saying that Physics was beyond our reach and Logic did not concern us: all that did concern us was Ethics. Dialectical reasoning, he said, are like spiders’ webs, which, though they seem to display some artistic workmanship, are yet of no use.
As Brad Inwood (2018) explains it,
Aristo, from the Aegean island of Chios, argued that physical theory (including what we would call metaphysics) and logic were unproductive intellectual indulgences. Opposing him was Cleanthes, who emphasized natural philosophy (physics) and theology as well as ethics and logical theory. The difference between the two foreshadows important later tensions in the school. On one side you have a Large Stoicism, inclusive of all kinds of intellectual activity, arguing that the ultimately ethical goal of philosophy required knowledge across the entire range of topics of intellectual enquiry; this is the line taken by Cleanthes. On the other side you have Minimal Stoicism, the line taken by Aristo; like the Cynics, he focused exclusively on ethics: the practical application of human reason to the job of making one’s life better .
As an aside, Aristo was no insignificant Stoic philosopher, but was rather influential for centuries to come. Some scholars  reckon that it was the writings of Aristo that finally transformed the 25-year old Marcus Aurelius into a full-fledged philosopher as opposed to being a dabbler in rhetoric, as evidenced in his letter to his rhetoric teacher Marcus Fronto.
The rejection of Stoic physics and logic as something irrelevant to practitioners is as old as Stoicism itself. Or even older than Stoicism if we consider the views of Cynics as well. The Stoic philosopher, Posidonius, of the middle Stoa did not reject Stoic physics or logic, and yet,
[Posidonius] clearly treated ethics as the ultimate point of philosophy.
The last undisputed scholarch
Panaetius ignored Chrysippus and rejected the notion of a phoenix cosmos.
While Roman Stoics such as Musonius Rufus, Epictetus, Marcus Aurelius and Seneca did not reject Stoic metaphysics, they did not give prominence to these topics either. The hugely prolific Seneca practically ignores Stoic physics in his writings except for what he says in Naturales quaestiones(which is not a systematic work, but a collection of facts of nature from various writers, Greek and Roman, many of which are curiosities). Epictetus and Marcus mention Stoic physics even less in their writings. Roman Stoics go out of their way to state explicitly (although not too often) that many of these theoretical topics maybe superfluous. Here is Epictetus talking about Stoic metaphysics:
What do I care whether everything that exists is made up of atoms, indivisibles, or fire and earth? … Questions that are beyond our understanding, we should ignore. It may well be that the human mind cannot grasp them. Even if you think they are perfectly understandable, what’s the use of understanding them? Should we not say those who think these things are an essential part of a philosopher’s knowledge are creating unwanted problems for themselves?
Musonius Rufus also talked against the multiplicity of concepts and argued for (what appears to me to be) Stoic minimalism.
Nor is there any need for students to master all this current mass of precepts … These theories are enough to consume a whole lifetime.
We can also find many passages in Meditations that state that Stoic principles will work even if we don’t accept its metaphysics. For example,
Either all things proceed from one intelligent source and come together as in one body, and the part ought not to find fault with what is done for the benefit of the whole; or there are only atoms, and nothing else than mixture and dispersion. Why, then, are you disturbed?
Of course, there is the academic contention that we need Stoic physics and Stoic logic because they provide the foundation for Stoicism. Without necessarily challenging that point of view, I would like to relate my personal experience as a practitioner. While I have been familiar with Stoicism for decades, I have not read much about Stoic physics and Stoic logic until last year. After studying Stoic physics and Stoic logic more closely last year (Including a full length book on Stoic Physics) I can confidently say my understanding of Stoicism has not increased any more than it did after reading one of the Harry Potter books. In my view, for a practitioner, neither Stoic physics/metaphysics nor Stoic logic adds anything useful to the understanding of Stoicism. Going back to my analogy, physics has nothing to teach a high wire artist on how to perform well.
Stoicism has also been acknowledged as the source of some models of psychotherapy, most prominently Cognitive Behavior Therapy (CBT) and Rational Emotive and Behavior Therapy (REBT). It is also used by the US military and the NHS in the UK. In all these cases (where the application of Stoic principles is the focus), Stoic physics or logic plays – and can play – no part. I believe it is fair to say that the resurgence of Stoicism in the past decade is largely due to practitioners for whom Stoic physics and logic hold no relevance.
Because the minimalist believes that Stoic ethics is a self-contained system that can be built on verifiable and self-evident truths (or on axioms if necessary), she avoids all religious and metaphysical explanations in preference to potentially provable propositions. (A Stoic minimalist, however, is not necessarily against religion or metaphysics.)
Stoic ethics is a self-c0ntained logical system. For a minimalist, Stoic ethics is a rational, self-contained system that can be built from the first principles and the essence of Stoicism can be found only in Stoic ethics rather in physics or logic.
What Did Stoics Mean by Ethics, God, Virtue and Nature?
Ancient Stoics used four concepts repeatedly: god, ethics, virtue and nature. What did they mean by these words? It is not a question of simple translation. Meanings of words change over time. When, in a Sherlock Holmes’ story, Conan Doyle described someone as ‘gay’, he certainly did not mean homosexual. It gets more complicated when we try to translate 2,000-year old Greek or Latin into 21st Century English. Even scholarly translations run into problems such as these:
- Should we translate words as they were written, or as they were understood at that time or as they mean now?
- If an expression meant something different when it was written, should the translator still use the same expression or its equivalent today?
- If a word-for-word translation makes a passage difficult to understand (because of the differences between ancient Greek or Latin and modern English), should a translator still stick to the way it was written or change it so the meaning and import of the passage is better understood?
- What do we do with the gaps in ancient texts and corruption of textual material, as is the case with Meditations and other ancient Stoic works?
These are not just theoretical issues. As an example, both Amy Richlinand C.R. Haines translated Marcus Aurelius – Fronto communications ‘word-for-word’. However, because Richlin uses current slang where Haines uses Victorian slang, their translations read differently, in some places substantially so. Because of their different perspectives, in some places where Haines’ translation (which is titled Marcus Cornelius Fronto: Correspondence) is flat, Richlin’s (which is titled Marcus Aurelius in Love) is lurid.
When we come to words with religious and moral overtones such as god, ethics and virtue, the issue gets more complicated. Does it make sense to understand these terms as we commonly understand them now? The minimalist believes that ancient Stoic writings were not religious scriptures. If we are to understand the essence of Stoicism, we should be less concerned about the exact words that ancient Stoics used, but interpret them to correspond to what they would mean now. Let’s start with ethics.
Ethics, as we understand the word now, relates to moral right and wrong. However, Stoicism is a eudemonic philosophy and its goal is eudemonia (happiness or the good life, however one defines it). Stoic ethics was not concerned with moral right or wrong. What is ethical is whatever contributes to eudemonia. What is unethical is whatever doesn’t contribute to eudemonia.
STOIC ETHICS. The minimalist holds whatever contributes to happiness (eudemonia) as ethical and whatever moves away from happiness as not ethical.
Similar to ethics, ‘virtue’ has also moral and religious overtones. What did ancient Stoics mean by virtue? According to many Stoic scholars such as Christopher Gill, “virtue is a form of expertise or skill, knowledge of how to live well.”
STOIC VIRTUE. The minimalist accepts the definition that Stoic virtue is the knowledge needed to achieve happiness.
Ancient Stoics are considered to be pantheists. Christopher Gill says that god in Stoicism stands for the “inherent rationality and order” of the universe. For the ancient Stoics god is the totality of nature. If god is the totality of nature and its ‘inherent rationality and order’, the term ‘god’ can be interpreted as ‘the way things are’ or ‘the way things work’. Yet, when one read a passage like this in Discourses,
How else could it come about so regularly … when he [god] tells plants to flower they flower, and to bud, they bud, and bear fruit, they bear it, and to bring their fruit to ripeness, it ripens … how else could it be that the moon waxes and wanes and the sun approaches and recedes …
the image it evokes is of a god that is no different from the Judeo-Christian God of the Bible (and many other religious traditions). It appears that god has intent and he tells the universe what to do. From this perspective, the description of god as seen in the writing of Stoics like Marcus Aurelius or Epictetus can hardly be distinguished from any other description of god (except that the Stoic god is not vengeful, does not punish or reward human beings.)
The philosopher Plotinus who was, among other things, influenced by Stoicism even doubts if the ancient Stoics truly believed in god and offered this assessment:
[The Stoics] bring in god for the sake of appearances.
What does this all mean to a Stoic minimalist? Can an atheist or agnostic be a Stoic?
Stoicism is a prescription for action, no matter what happens or how it happens. So it doesn’t matter why something happened. . In this vivid passage, Marcus Aurelius dismisses – even mocks – our preoccupation with theory and points out that practice of Stoic ethics is all that matters.
The cucumber is bitter? Then throw it out.
There are brambles in the path? Then go around them.
That’s all you need to know. Nothing more.
Don’t demand to know “why such things exist.”
What we have control over is only what we are going to do next. Viewed this way, whether god made something happen or something happened randomly is of no importance to a Stoic. Either way, we have no control over the way things presented to us by the universe.
GOD. The minimalist views god as nothing more than things being the way they are.
To a minimalist, it matters little whether a Stoic believes in god or is an atheist or is an agnostic. It has no bearing on the practice of Stoicism.
The Stoic premise of living in accordance with ‘nature’ is a vague idea. But Stoics defined this in specific ways. In fact, Stoics talked about several types of “nature” that one should be ‘in accordance with’, using a process known as reconciliation. Hierocles argued that there were four types of reconciliation corresponding to the four cardinal virtues: self-reconciliation (wisdom), social reconciliation (justice), bodily reconciliation (courage), and external reconciliation (moderation). In short, we should live in accordance with human nature and the nature of this universe. Thus, to live without friction, we need to cultivate two types of accordance: accordance with human nature and accordance with the nature of the world.
What is in accordance with human nature? The thing that sets human beings apart from other animals is rationality. So to live according to nature is to live rationally. What is in accordance with the external world? It is accepting whatever happens as a given. Thus one who acts in accordance with nature acts rationally and does not struggle against reality.
STOIC ‘NATURE’. To the minimalist, ‘living in accordance with nature’ means accepting the world as is (over which they have no control) and acting rationally in response to what is (over which they do).
What Exactly is Stoic Minimalism?
So far we have discussed,
- Stoic ethics is the essence of Stoicism and it is eminently capable of standing on its own, without having to be propped up by Stoic physics, metaphysics and other gobbledygook;
- Stoic concepts like god, nature, ethics and virtue are better understood if we use their modern thought-equivalents rather than word-equivalents.
Now we are ready to explore the contents of Stoic minimalism.
The basic principle that has been around since the founding of Stoicism – the dichotomy of control – can be considered the cornerstone of Stoicism, summarized succinctly by Epictetus:
- Some things are up to us and others are not. [We can achieve happiness by confining our thoughts and actions to what is under our control.]
This first principle – that we can achieve happiness or Eudemonia by confining our thoughts and actions to things under our control (‘up to us’) and ignoring what are not (‘not up to us’) – contains the wisdom needed to achieve happiness, but we cannot achieve it by directly pursuing it, because doing so will have unintended consequences (such as overindulgence, uncontrolled greed, antisocial behavior, attaching too much importance to transient pleasures, etc.,) that may lead one in the opposite direction. Directly going after happiness is not the way to achieve it.
- One cannot achieve happiness by directly pursuing it.
So what is the way to achieve it? The practice of excellence. Eudemonia or ‘excellent disposition of the soul’ is the result of pursuing excellence (virtue) and this is all we need to concern ourselves with and it is the only good. But if the aim of Stoicism is achieving happiness, how can practicing excellence be the only good? There are many answers to this.  One way to look at this is to consider our natural state as eudemonic. To achieve it, all we need to do is to remove hindrances to it through pursuing excellence. We don’t have to do anything. As we remove the hindrances (or vices) of foolishness, injustice, cowardice, intemperance and the rest, we achieve the eudemonic state.
- Practicing excellence is the only good.
The corollary to the third principle is that, to achieve excellence as conceived by Stoicism, we need special knowledge in four different areas: self, others, our desires and our aversions. The special knowledge we need is wisdom (in all our dealings), justice (in dealing with others), moderation(in dealing with our desires), and courage (in dealing with our aversions). Having these four types of special knowledge or virtues together leads to excellence.
3a. Excellence is achieved through four types of special knowledge: wisdom, justice, moderation and courage.
This, in my view, is Stoic minimalism. Rationality is the principle, virtue is the means, and eudemonia is the end. Anyone who accepts these three principles, in my opinion, is a Stoic irrespective of whether they agree or disagree with anything else about Stoicism.
When we thus cut out the dead bark of Stoic physics, logic and religiosity, “its paradoxes, and the willful misuse of language, … its extravagance,” and get rid of our devotion to a literal interpretation of what was spoken 2,000 years ago in a different time, a different culture, and a different place, out comes a shiny, timeless philosophy of the essence of Stoic wisdom, Stoic minimalism.
I don’t profess to be a Stoic (or any other kind of) scholar. So let me stand back and give the final word on Stoic minimalism to the well-known Stoic scholar, Brad Inwood:
The narrow focus on ethical improvement is also an authentic component of ancient Stoicism.
That is also my response to the critics of Stoic minimalism who are dismissive of it as just “life-hacking” and not “real Stoicism”.
 John M. Cooper, Pursuits of Wisdom. Princeton University Press, 2013.
 Even though the available works of Epicurus are also limited, they are consistent because they are the work of single person.
 Seneca, Letters to Lucilius, XXXIII.11
 Lawrence Becker. A New Stoicism. 2nd edition. 2018.
 Ariston of Chios. Encyclopaedia Brittanica.
 Different from similar sounding Aristo(n) of Ceos, a Peripatetic philosopher.
 Diogenes Laertius, The Lives of Eminent Philosophers, VII.161.
 Brad Inwood, Stoicism: A Very Short Introduction to Stoicism, Oxford, 2018.
 Also see Introduction. Stoicism: An Intellectual Odyssey in The Cambridge Companion to the Stoics. Edited by Brad Inwood, Cambridge University Press. 2003.
 C.R. Haines. Marcus Cornelius Fronto: Correspondence Vol. I. Loeb Classical Library, 1919, see footnote 1 on page 218.
 Amy Richlin. Marcus Aurelius in Love. The University of Chicago Press, 2006, see endnote 12 on page 142.
 Brad Inwood, A Very Short Introduction to Stoicism, Oxford, 2018.
 M. Andrew Holochuk. The Stoics: A Guide to the Perplexed. New York: Continuum, 2008. (Panaetius did not reject Stoic physics completely but did not accept Chrysippus’ version of it. What is of relevance here is that no matter who believed what version of Stoic physics, it made zero difference to Stoic ethics.)
 Seneca, Natural Questions, Volume I: Books 1-3 & 4-7. Tr. Thomas Corcoran, Loeb Classical Library. 1971
 From the Wikipedia entry Naturales quaestiones.
 Epictetus, Fragments. (Emphasis mine.)
 Musonius Rufus, Lecture 11.
 Marcus Aurelius. Meditations. IX.39
 See for example, Massimo Pigliucci. How to be a Stoic, 2018. Basing his arguments on Pierre Hadot’s original exposition (The Inner Citadel, 1998), Pigliucci makes the point that discipline of desire and the virtues that relate to them (courage and temperance) are based on Stoic physics. Even if this is true, it does not follow that Stoic ethics can only be derived from Stoic physics and Stoic logic, and not in any other way. A sufficient condition cannot be assumed be a necessary condition.
 I acknowledge the fact that personal experience is not proof. But, I don’t think it is totally irrelevant to the discussion either.
 Samuel Sambursky, Physics of the Stoics, Princeton University Press, 2016.
 Some scholars argue that while this is a problem with ancient Greek, it is not so with Latin. But as I point out elsewhere in this article, ancient Latin texts are not totally exempt from multiple interpretations.
 Amy Richlin. Marcus Aurelius in Love. The University of Chicago Press, 2006.
 C.R. Haines. Marcus Cornelius Fronto: Correspondence Vol. I & II. Loeb Classical Library, 1919.
 Christopher Gill, What is Stoic Virtue? Modern Stoicism, 2015. (http://modernstoicism.com/what-is-stoic-virtue-by-chris-gill/)
 Christopher Gill, in Introduction to The Discourses (Tr. Robin Hard), London: J. Dent, 1995.
 Epictetus. The Discourses I.14.3 (Tr. Robin Hard), London: J. Dent, 1995.
 Plotinus. The Philosophy of Plotinus: Representative books from the Enneads. Appleton-Century-Crofts, 1950.
 Marcus Aurelius. Meditations. VII.50. (Tr. Gregory Hayes),
 Ramelli, I. (2009). Hierocles the Stoic: Elements of Ethics, Fragments, and Excerpts. Translated by D. Konstan. Society of Biblical Literature: Atlanta, GA.
 Epictetus. Discourses I.1.
 Eudemonia (eu=good, daimonia=spirited) is a single concept with multiple shades of meaning. For example, when Socrates, Nelson Mandela and Gandhi were thrown in prison, they had means of not being imprisoned in the first place or means of getting out. They chose not to because doing so would have put them in conflict with their nature and made them unhappy. In fact, Gandhi told the judge that he had no option but to send him to jail, which he was willing to accept completely, if the judge believed the law to be just. So what, to an outsider, is an unflourishing life was indeed a flourishing one for them. They did not consider a preferred indifferent as the source of their happiness.
 The idea that happiness cannot be achieved by directly pursuing it is a recurring theme in many disciplines. For example, John Stuart Mill, while discussing Utilitarianism, has this to say on happiness: “Those only are happy who have their minds fixed on some object other than their own happiness; on the happiness of others, on the improvement of mankind, even on some art or pursuit, followed not as a means, but as itself an ideal end. Aiming thus at something else, they find happiness by the way.” John Stuart Mill , The Collected Works of John Stuart Mill. e-artnow, 2017
 John Sellers. Stoicism. University of California Press, 2006.
 Mark Tullius Cicero. Paradoxa Stoicorum.
 A. A. Long (ed.) Problems in Stoicism, London: Athlone, 1971.
 This is not one of the standard explanations. A Stoic minimalist is free not to accept it as there are many alternative explanations.
 St. George Stock. A Little Book of Stoicism. Ten Cent Pocket Series No. 347.
 Brad Inwood, A Very Short Introduction to Stoicism, Oxford, 2018