What Teaching Was Thucydides Trying to Convey?
And Why It Remains So Important for Us Today
As we approach the close of the first quarter of the twenty‑first century, it is striking how gloomy our world must seem compared to how it might have looked at its outset. True, the immediate post‑Cold War period saw its share of civil wars and ethnic violence, but heading into a new century, at least in some circles in the West and perhaps elsewhere could still imagine that these were merely the aftershocks of the turbulent one still ending.
Few books on war and politics shed such light on present circumstances as one of the earliest we still have: Thucydides’ magisterial history of the Peloponnesian War.
Today, however, with two decades of costly occupations behind us, the onset of the first major cross‑border land war in Europe since World War II, and escalating geostrategic competition with a still‑rising China in the Pacific, matters look quite a bit different. It is only natural that we might begin to cast about for sources that could illuminate our situation. And, perhaps ironically, few books on war and politics shed such light on present circumstances as one of the earliest we still have: Thucydides’ magisterial history of the Peloponnesian War.
Over 2,500 years ago, Thucydides prefaced his great work with the hope that it would become a “possession for all time” (Thuc. I.24.4)—a phrase that has proven to be one of the more prophetic introductory passages of any work, ever. Two‑and‑a‑half millennia on, we are still reading and discussing his account. This is, of course, the case for the article you’re reading right now, but it’s also routinely referenced in discussions of foreign policy, survey courses on international relations, the scholarly literature on causes of war, the “Thucydides trap” hypothesis, and so on.
And yet, the foregoing characteristically terse comment by Thucydides is perhaps the only place where the man himself signals his intentions to the reader. Unlike other seminal writers in the history of political thought and historiography like Tacitus, Machiavelli, or Nietzsche (none of whom is by any means straightforward in his own right), we are given precious little else to go on as far as what Thucydides personally wishes to communicate to us across the centuries. And so, while we continue to read and discuss this “possession for all time,” we necessarily find ourselves debating the question: what was Thucydides trying to tell us?
There is, of course, no simple answer to this question, and our understanding is probably complicated by the way that Thucydides has largely entered public consciousness by way of oversimplified and mistranslated pull quotes (e.g., “the strong do what they will, and the weak suffer what they must”), not to say the many banal sayings misattributed to him (e.g., “A nation that makes a great distinction between its scholars and its warriors will have its laws made by cowards and its wars fought by fools.”).
But what is the work about? As Thucydides tells us at the outset, his text details the history of the great war between the Athenians and the Spartans, which we know as the Peloponnesian War, that lasted from 431‑404 BC. Though this description requires immediate qualification: his history (particularly in the opening sections, which scholarly convention refers to as “the archaeology”) extends back well before the start of the war to provide us with a broader understanding of the immediate political dynamics leading up to the outbreak of war, as well as the material and structural elements of geopolitical conflict in the deeper history of the Hellenic world.
Meanwhile, at the other end of things, his work (as with Homer’s Iliad and the Trojan War) does not cover the entirety of the war. Thucydides’ account ends midway through 411, and the eighth and final part of his work is generally agreed to have been unfinished, though scholarly disagreement remains as to just how incomplete was the version that has come down to us. (For an account of the war’s final years, one must consult Xenophon’s Hellenika, which consciously picks up the narrative where Thucydides leaves off.)
The war itself (as Thucydides outlines) arose among the primary victors of the Persian Wars (449‑449 BC), a series of invasions of Greece by the Persian Empire recounted by Thucydides’ predecessor, Herodotus. The individual Greek city‑states successfully banded together to repel the invaders under the leadership of its greatest maritime and greatest military powers (respectively, Athens and Sparta). In the aftermath of the Persians Wars, there was some disagreement over what to do with the alliance that had been painstakingly built over time. Most of the other Greek citystates were happy to disband and return to their condition of independent self‑rule. The Athenians, however, under the leadership of the brilliant Themistocles—who had also led them to victory in the Persian Wars—argued for the necessity of maintaining a military alliance, first to retake further Hellenic cities from Persian control and second to defend indefinitely against future imperial incursions. To that end, they established a confederacy, known as the Delian League, which pooled resources for the defense of the Greek city‑states under Athens’ leadership. Over the course of the subsequent half‑century, Athens’ relative power grew in proportion to its allies’ willingness to commit money rather than ships toward the common defense; thus, many of those same allies transitioned to become tributaries over time.
By 432 BC, the Spartans felt compelled to break the existing peace between the Greek city‑states and oppose the continued rise of Athens, though they sought to find a pretext for doing so. As Thucydides famously remarks, “The real cause [of the war] I consider to be the one which was formally most kept out of sight. The growth of the power of Athens, and the fear which this inspired in Sparta, made war inevitable” (Thuc. I.23.4).
Yet the immediate catalyst for the war was not in fact a direct quarrel between Athens and Sparta, but a tertiary conflict between the associated city‑states of Corinth and Corcyra (not unlike the way that the spark for World War I ignited in Hapsburg‑annexed Bosnia rather than the Franco‑German border). The Corinthians appeal to Sparta to marshal not just against their immediate enemy, Corcyra, but against its great ally, Athens; and, after some debate, the Spartans agree. This initiates the first period of the war, sometimes called the “Archidamian War” after the reigning king of Sparta (who, ironically enough, argued against the Spartan declaration of war).
From there, the war waxes and wanes for some years, with no clear champion, reaching a negotiated settlement in 421 BC, during what is called by scholars the Peace of Nicias. That peace is ultimately broken when Athens, swayed by the charismatic Alcibiades (who appears in a number of Socratic dialogues written by Plato and Xenophon), decides to launch an invasion of Sicily to conquer the Greek city‑states there (415‑413 BC). That invasion proves to be a cataclysmic disaster in its own right and also brings the Spartans back into the fray, along with shrewd factions of the Persian Empire who see an opportunity to weaken the Hellenic world.
In spite of a good deal of internal political turbulence, including a minor revolution, Athens mounts a recovery, stabilizing its government and effectively suppressing its rebellious allies and tributaries. At the point of the Thucydidean narrative’s untimely end in 411 BC, the outcome of the war remains very much uncertain. Ultimately, however, we know (and Thucydides knew), that Athens would prove unable to successfully manage its domestic political strife, and even its vaunted navy finally comes to defeat at the Battle of Aegospotami, leading it to finally surrender in 404 BC. This signals the permanent decline of Athens—up to that point the cultural and intellectual pinnacle of Greece—and perhaps ultimately of the Hellenic world itself.
Thucydides’ Method
But to return to the question of Thucydides’ own intention, we cannot think through the meaning of Thucydides’ history without saying something about his method. The first words of the work are “Thucydides, an Athenian, wrote the history of the war” (Thuc. I.1.1). Without belaboring it, he reminds us that this account is not an Olympian one, but one authored by a single man and a citizen of one of the major combatant citystates to boot. Thus, from the beginning, we are given to know that this is perhaps inevitably a partial perspective on the war (once again, there is very little that the postmodernists have discovered that was not already present in world literature...).
Thucydides’ work is of course a military history and is replete with astonishing battle scenes, like Matinaea, Delium, Amphipolis, and Sphacteria. But it is also a political history, and as befits a culture for which rhetoric was the supreme political art, the battles are (if anything) outdone by the great rhetorical set pieces: the congress of the Peloponnesian confederacy, where the declaration of war is debated; the Mytilenean Debate, in which the fate of a city is decided; and perhaps above all the Melian Dialogue, in which justice and power are framed in the starkest of terms.
Indeed, it would not be incorrect to say that the speeches that appear throughout are as much a part of the action of the narrative as the fighting itself. And yet one of the supreme oddities of the work is Thucydides’ decision to “make the speakers say what was in my opinion demanded of them by the various occasions, of course adhering as closely as possible to the general sense of what they really said” (Thuc. I.22.1).
We can say, then, that Thucydides is providing us with amplified or sharpened versions of a range of perspectives without, however, articulating his own perspective (at least directly). Yet one of the most common misreadings of Thucydides—as with superficial readings of Plato or Shakespeare— is to attribute to him a viewpoint that issues from the mouth of one of the personages featured in his work.
About himself, he tells us relatively little. We know he contracted and survived the great plague that befell Athens in 430 BC, and which forms a crucial part of the second part of the work. Most importantly, we know he was a general who fought unsuccessfully against perhaps Sparta’s greatest commander, Brasidas. And this failure led to his exile at the hands of punitive Athenians—which was in turn perhaps the condition for his being able to write the great work of which this essay is the subject in the manner in which he did. Some scholars have perceived elements of bitterness in his narrative arising from this misfortune, but I for one don’t see it. His sole commentary on the matter is this: “It was also my fate to be an exile from my country for twenty years after my command at Amphipolis” (Thuc. V.26.1)
His method may be loosely characterized as “literary”—a somewhat misleading term that will have to stand for now. Why literary? First, despite his reputation as a cold‑eyed realist, his narrative runs dramatic circles around the basic synopsis of the war provided above.
The Thucydidean account provides the alert reader with an education in how to think about the war in a non‑didactic way.
It is not simply that Thucydides gives to Pericles such an extraordinary panegyric to his city and its democratic regime; it is that he then immediately follows it with a harrowing account of the plague that befalls Athens, as though to undercut all that came before. Similarly, the infamous destruction of Melos by Athens is immediately succeeded by the first discussion of the invasion of Sicily, which will prove similarly ruinous to Athens (the great classicist Thomas Arnold has called the seventh part of the work, which details this invasion and its consequences, the greatest prose narrative of the ancient world).
Similarly, as Nietzsche noted in various writings, his use of speeches is heavily dialectical—whether following a given speech with an opposing speech, or following it with some action or development in the war that complicates our understanding of what we have just read. In such ways does the Thucydidean account not merely provide us with the facts and details of the war but also provides the alert reader with an education in how to think about the war in a non‑didactic way.
The Regime Question
The speeches naturally reveal something characteristic about the speaker and about a particular point of view. But they also seem to reveal something characteristic about the regime of which the given speaker is a citizen (in the original Greek, the word translated as ‘regime’ is politeia, a term that denotes the comprehensive set of formal and informal political, social, and economic arrangements that characterize a given city‑state, including but not limited to its form of government). We rarely forget the fact that this is a conflict between democratic Athens and oligarchic Sparta. But what does that mean, exactly?
The point is not that a regime necessarily produces a specific policy or strategic vision. After all, during the inaugural debate over the war, we see Spartans arguing both for and against going to war. Or during the Mytilenean Debate, we see Athenians arguing both for and against the destruction of Mytilene. But the regime does produce in its citizens a certain way of arguing—a mode of considering political alternatives.
The oligarchic Spartans are both stolid and honor‑loving. Thus, they are only roused to war by the furious Corinthians, and their prudent king Archidamus very soberly cautions against embarking on such a dangerous and uncertain enterprise as open warfare against Athens and its growing empire. Yet the intemperate Sthenelaidas ultimately carries the day during the debate over going to war, having been pricked by accusations of cowardice.
Meanwhile, the democratic Athenians are peripatetic, impulsive, and dynamic. In a clever (literary!) move, the most comprehensive single description we have of them is provided by the hostile Corinthians:
The Athenians are addicted to innovation, and their designs are characterized by swiftness alike in conception and execution; you have a genius for keeping what you have got, accompanied by a total want of invention, and when forced to act you never go far enough. Again, they are adventurous beyond their power, and daring beyond their judgment […]. They are swift to follow up a success, and slow to recoil from a reverse. Their bodies they spend ungrudgingly in their country’s cause; their intellect they jealously husband to be employed in her service […]. To describe their character in a word, one might truly say that they were born into the world to take no rest themselves and to give none to others. (Thuc. I.70.2‑3,5‑6,9).
Against mainstream contemporary Western associations of democracy with peace and non‑domination, Athenian democracy seems to go hand in hand with empire—a point that the great Athenian statesman Pericles unambiguously celebrates in his famous Funeral Oration. And after Pericles’ death, he is succeeded by demagogic figures like Cleon, whose influence on the people proves less than salutary.
Yet it would be a mistake to assume, as some scholars do, that Thucydides’ account is necessarily anti‑democratic. For the same city (i.e., Athens) is capable of magnanimity over wayward tributaries (as they ultimately are after the Mytilenean revolt). And in the wake of the disastrous Sicilian Expedition, Athens manages to stave off civil conflict at home and marshal the resources to continue prosecuting the war for almost another decade. Meanwhile, it is another democracy—Syracuse—that hands Athens its most stunning single defeat.
Finally, as Thucydides himself carefully reminds us (and Pericles bluntly reminds us), the relative moderation of the Spartans in their dealings with the other Greek citystates is premised upon a shocking and brutal form of control closer to home, as their enslavement of their sizable neighboring population prevents them from spending too much time abroad. Thus, the question of regime type proves to be of great significance when it comes to the conduct of Hellenic city‑states during the war, but not in any straightforward or programmatic way.
Inside/Outside
Another recurring theme of the Thucydidean work is the inseparability of war and politics—the way that the political dynamics within city‑states supervene on the warring between them, and vice versa. We first see this in Thucydides’ starkly memorable description of the terrible plague that strikes Athens in the early years of the war. First, because the particular virulence (and possibly the transmission of the plague itself) was due to the swelling population density that resulted from peripheral estate‑holders fleeing to the safety of the city as the Spartan invaders attacked their lands. But second, because of the way that the egoistic logic of the Athenian worldview fares poorly under the extreme pressures of random death and social breakdown.
This is most explicitly the case with Thucydides’ description of the civil warfare that erupts in the city of Corcyra and spreads throughout the Hellenic world. As both Athens and Sparta seek to gain leverage over the city by propping up their preferred democratic or oligarchic faction, respectively, the stresses begin to tear the city apart, and factional conflict gives way to general violence.
And it is clear, meanwhile, that Thucydides intends his depiction of the revolution in Corcyra to serve as a stand‑in for what became an increasingly general phenomenon during the course of the Peloponnesian War:
So bloody was the march of the revolution, and the impression which it made was the greater as it was one of the first to occur. Later on, one may say, the whole Hellenic world was convulsed; struggles being every, where made by the popular chiefs to bring in the Athenians, and by the oligarchs to introduce the Lacedaemonians. In peace there would have been neither the pretext nor the wish to make such an invitation; but in war, with an alliance always at the command of either faction for the hurt of their adversaries and their own corresponding advantage, opportunities for bringing in the foreigner were never wanting to the revolutionary parties. (Thuc. III.82.1)
Civil war, then, is not some sort of separate business from inter‑state or international war; indeed, it is frequently both the cause and the effect of such wars. Napoleon’s invasion of Spain gave us the Peninsular War, with all that entailed. World War II saw horrific bloodletting away from the main battlefield theaters as irregular combatants fought one another for control across the Balkans (Yugoslavia and Greece), in China, and elsewhere. The Cold War period saw much the same, as the United States and the Soviets armed their preferred proxies and set them loose across the Middle East, Southeast Asia, Central America, and so on.
Similarly, the so‑called Sicilian Expedition, in which the Athenians mount a ruinous attack on the distant city of Syracuse, has come to serve as a kind of ur‑example of imperial overstretch, and is frequently recalled in light of more contemporary examples—such as the United States in Vietnam, or the Soviets in Afghanistan.
But here one must note Thucydides’ own judgment, in his obituary to Pericles, that the disaster was due less to the nature of the operation itself than to civil strife at home overtaking the normal course of political deliberation—what we might call the introduction of logics of foreign warfare into the city itself.
[The Sicilian Expedition] failed not so much through a miscalculation of the power of those against whom it was sent, as through a fault in the senders in not taking the best measures afterwards to assist those who had gone out, but choosing rather to occupy themselves with private squabbles for the leadership of The People, by which they not only paralyzed operations in the field, but also first introduced civil discord at home. (Thuc. II.65.11)
Finally, it is not incidental that such events as the destruction of Melos and the catastrophic Sicilian expedition, among others, occur nearly two decades into the larger war. There is a sense in which the experience of the war hardens the Athenians into the very thing that they are accused of being at the outset.
Thucydides the Realist?
Thucydides is routinely referred to (and occasionally derided) as a “realist.” But what does this mean? He certainly never refers to himself this way (and, as the above discussion of his style should make clear, one can hardly imagine him doing so). Indeed, such a term is wildly anachronistic to his time and place. What other writers who refer to him thusly tend to have in mind is typically the ethos expressed by key figures in the work— for example, the nameless (and unofficial) Athenian envoys to Sparta in the period immediately preceding the onset of the war who defend their empire with reference to what they claim are the core motivations of fear, honor, and interest.
Thucydides is routinely referred to (and occasionally derided) as a “realist.” But what does this mean?
And, perhaps more broadly, such writers may be thinking of Thucydides’ own dispassionate portrayal of harsh truths about the human condition and political life, as found in his accounts of such events as the plague in Athens or the terrible civil war in Corcyra. Once read, it is difficult to forget judgments like: “In the confusion into which life was now thrown in the cities, human nature, always rebelling against the law and now its master, gladly showed itself ungoverned in passion, above respect for justice, and enemy of all superiority” (III.84.2). No less a writer than Nietzsche praises this quality in Thucydides in Twilight of the Idols as “the last manifestation of that strong, stern, hard matter‑of‑factness instinctive to the older Hellenes.”
Yet it must be said that Thucydides is not callous in his depictions. Indeed, he is keenly alive to the reality of human suffering, which is an inevitable consequence of a great and terrible war. He accords surprising space to the plight of strategically insignificant but heroic Plataea. And he draws our attention to the awful fate of the beaten Athenians in the aftermath of their failed attack outside of Syracuse, just as he draws it to the massacre of helpless schoolchildren at the hands of Thracian mercenaries in the pay of Athens.
Such is the Homeric sweep of the Thucydidean narrative: we have the sense of a God’s‑eye (or Zeus’ eye) view of the full panorama of the war, with all the triumph and suffering it entails.
Finally, Thucydides presents in a non‑didactic way an extraordinarily compelling account of the interplay between justice and necessity, which has proven to be a perennial theme in political life up to the present day (just consider the arguments on all sides for Russia’s ongoing invasion of Ukraine). From his discussion of the causes of the war, through the many Athenian defenses of their empire, to the remarkable speech of Diodotus during the Mytilenean Debate, the reader of the Thucydidean work is led to complex practical considerations of how we are to think about the role of justice in political life.
Throughout the work, various speakers appeal to the concept of necessity as something that absolves us of moral censure for our actions. One does not, after all, condemn the lion for killing and eating a wildebeest.
So, too, the Athenians claim at the outset of the war, the other Greek city‑states ought not condemn them for seizing an empire when the opportunity afforded itself to them. In a curious sense, we might even say that it would be unjust to do so; that justice, in other words, requires that we not apply standards of justice too stringently where the harsh necessity is concerned.
It is one thing to posit that ours is a universe in which the strong imprint their will upon the world while justice is silent; quite another to actually live in that universe.
All of this is to say that while it is conventional to frame these debates as “might versus right” or “power versus justice,” these are misleading schema. For the question of justice runs like a skein through nearly every speech or debate in the work. If we understand justice to mean “what is fitting” or “what is owed” in our world, then the different protagonists can be seen advancing various accounts of justice, albeit with varying degrees of plausibility and coherence. One of the reasons the Thucydidean text remains compelling so many centuries on is that we can observe political actors grappling intensively with the problem of justice within the context of their immediate practical concerns.
It is one thing, to claim absolution for oneself; another to see one’s own impulses toward freedom or empire against a universal backdrop.
The trouble for the Athenians, meanwhile, is that it is not such an easy thing to apply this mode of thinking in any consistent way. After the Mytileneans revolt against Athens and are subsequently brought to heel, the Athenians vengefully decide to put them all to death. But as pointed out by Diodotus, who argues against such a motion, it was a perfectly natural thing for a subjugated city to rebel. In language that recalls that of the defense the Athenians make on behalf of their empire, he observes:
Hope leads men to venture, and no one ever yet put himself in peril without the inward conviction that he would succeed in his design. Again, was there ever city rebelling that did not believe that it possessed either in itself or in its alliances resources adequate to the enterprise? […] [A]s long as poverty gives men the courage of necessity, or plenty fills them with the ambition which belongs to insolence and pride, and the other conditions of life remain each under the thralldom of some fatal and master passion, so long will the impulse never be wanting to drive men into danger. (Thuc. III.45.1‑2,4)
The Athenians ultimately heed his counsel and rescind their decision to destroy the entire city of Mytilene. But it is a close‑run thing, and as their initial impulse toward destruction indicates, it is simply difficult to internalize the logic of empire. It is one thing, in other words, to claim absolution for oneself; it is another thing to see one’s own impulses toward freedom or empire against a universal backdrop.
And this problem is manifested not only in the Athenians’ management of their empire, but in their pious apprehension that they ultimately may be subject to some higher law for their transgression. How else to explain the intention to execute the able commander Alcibiades for the supposed crime of disfiguring holy statues right upon the eve of their invasion of Sicily? Or their assigning command of that same invasion to Nicias, a man known not for his brilliance or audacity but for his decency and uprightness? Or there is the remarkable decision, which occurs too late to be recounted by Thucydides but is reliably recorded by Xenophon, to put to death their naval commanders for their failure to collect the bodies of the dead following their great victory at Arginusae.
It is one thing, in other words, to posit that ours is a universe in which the strong imprint their will upon the world while justice is silent; to say, as Pericles does, that “we have forced every sea and land to be the highway of our daring” for evil or for good. It is quite another thing to actually live in that universe.
One of the reasons the Thucydidean text remains compelling so many centuries on is that we can observe political actors grappling intensively with the problem of justice within the context of their immediate practical concerns.
Sempiternal Perplexity
In the end, key parts of this work refuse to yield up their mysteries in any definitive way. How are we to understand Thucydides’ claim that Spartan fear of Athens’ aggrandizement was the true cause of the war, or his claim that of all men who died in the course of the war, the hapless Nicias least deserved his fate? Such passages veer close to what the Greeks called aporia: an insoluble puzzle that induces perplexity in the reader or listener.
But is this so different from the situation that political agents face anyway—even and especially today? War is, after all, the supreme condition under which the highest‑stakes decisions must be undertaken in the absence of certain knowledge. And even hindsight does not fully reveal the correct course of action. We still debate the relative merits of George McClellan’s leadership of the Army of the Potomac, of Neville Chamberlain’s appeasement of Hitler, of Charles de Gaulle’s withdrawal from Algeria, of Cao Cao’s strategic errors at the Battle of Red Cliffs, and so on.
So too with the events of the Peloponnesian War. Examples abound: whether Pericles’ conservative strategy was the correct one, whether the Sicilian Expedition was an error of planning or execution, whether the twin destructions of Plataea and Melos were acts of necessity or cruelty.
In these and many other epi‑sodes, Thucy dides guides us without explicitly revealing his lessons. In this way, he recreates the experience of war in his monumental text. That we return to it time and time again to re‑experience it is just one part of the measure of his achievement
