The motto of Klemens von Metternich’s family coat of arms demanded Kraft im Recht – strength in law. The law stood for an order that excludes arbitrariness and violence, securing the conditions in which citizens might develop intellectually, economically and freely in their relations with one another and with the state. The strength represented everything that sustains the state: the executive power of government and the military, as well as the social ethos that can protect order without recourse to physical violence. Metternich understood that, for states to flourish, both qualities were essential. Anarchy or tyranny stemmed from their exclusion or mutual estrangement from one another.

Metternich entered the University of Strasbourg in November 1788, at the age of 15, and enrolled on the Matricula Serenissimorum et Illustrissimorum, the register of the highborn. His daily routine, as he described it to his father in the week of his matriculation, consisted of: a morning at lectures or with his tutors; an hour of science followed by an hour of music in the afternoon; and, at four o’clock, attendance, with his brother Joseph, at a course of historical lectures. He played the violin with aptitude. He attended the salons, some intellectually stimulating, others purely convivial. He studied law under the distinguished Professor Christoph Wilhelm von Koch, who lectured on the Peace of Westphalia and on the comparative history of revolutions. Metternich rode, fenced, took out a subscription to the Strasbourg Comédie. Strasbourg was one of the best universities in Europe in those last years of the old order, far more cosmopolitan in composition than Oxford, Cambridge or the German universities: a quarter of its students came from outside France – Germans, Habsburgs, Russians, English, Swiss.

In July 1789, Metternich watched from the streets as a drunken mob plundered the Strasbourg Stadthaus, his first direct experience of revolution and the violence of the multitude. Six years later, at 21, he was in London, where he met Pitt and Burke, dined with Fox and Grey and Sheridan, listened to debates in the Lords and the Commons, and sat for hours in Westminster Hall as the trial of Warren Hastings dragged into its sixth year of melodramatic abuse. He was absorbing the principles of the English constitution – which he admired – and the skills of statecraft through direct encounter with its greatest practitioners, at an age when he possessed no diplomatic standing whatsoever and no professional reason to be there at all.

To understand Metternich’s intellectual formation is to recognise what the contemporary debate about the international order consistently fails to see. That debate has settled into a familiar and increasingly sterile pattern – legalists on one side, self-described realists on the other – and it proceeds as though the figures who actually built and operated the order had nothing to teach us beyond the confirmation of positions already held. The world Metternich inhabited constitutes the richest period of European diplomacy, something much more substantial than an empty parenthesis between two peace conferences in the grand halls of Vienna and Versailles. It was the epoch of the last polymaths, active generalists and exceptional individuals, both in the sense of ability and of improbability.

Between Lord Castlereagh’s suicide in 1822 and the disaster of 1914 lies the century of Metternich and Palmerston, of Disraeli and Bismarck, of Count Cavour and the long afterlife of Talleyrand. These are the men who maintained the system in the courts and chancelleries of a Europe that was still cosmopolitan, as were the personalities that ruled it. Their doctrines, to the extent that they had them, were often mutually incompatible. If one could assemble them in a room – as it happened, in Berlin – the conversation would be magnificent and entirely without consensus. What connected them went beyond a superficial architecture of law and power. It was rather a shared type they could recognise in each other: the cultivated generalist whose political judgement was inseparable from a breadth of mind that would now be called, often with some hauteur, amateurish, and which was in fact the precondition for everything they achieved. Their statecraft was the by-product of a certain kind of formed personality. The question of what that personality required, and why we have ceased to produce it, is the question that is often missed in the noise of contemporary debate, in part because it is a more challenging and difficult question to answer, and a quality far harder to retrieve.

Approached in the round, Metternich emerges not primarily as a theorist, nor even as a constructive statesman. His gifts were those of an artist; he practised the skills of diplomacy with greater fluency than any contemporary except the cunning Talleyrand, from whom he had learnt many of the refinements of the game. The conventions are what the British politician Harold Nicolson – who had himself attended Versailles – later defined as the ‘old diplomacy’. It assumes that great powers form a concert and share responsibility for the international order. It accepts negotiation as a protracted undertaking forged in familiarity, and the primacy of confidential exchanges over public disputes. The system was formed while Metternich acted as ‘the coachman of Europe’, and reflected the qualities of his own personality. The system was inseparable from the man who operated it. When, in 1848, Metternich’s version of legitimacy could no longer accommodate the shifting realities of power and popular sentiment, the system collapsed alongside him, as he fled Vienna and the revolutionary mob.

Metternich demonstrates that the Congress system required a specific kind of mind and man to operate it. But it is Palmerston who shows us something more provocative still: that the supposed friction between law and interest, which many now take as an organising premise, is an altogether false binary.

The Pacifico Affair of 1850 is the case that everyone remembers, if they remember Palmerston at all. A Greek mob had destroyed the house of a British subject, a Gibraltarian Jew named Don Pacifico. Greek justice was not forthcoming and so Palmerston dispatched the Royal Navy’s Mediterranean fleet to blockade Piraeus and seize Greek shipping to the value of the British claims. France and Russia protested. The House of Lords censured him. His own Cabinet colleagues had failed, as usual, to read their Foreign Office papers. The Queen and Prince Albert were incandescent. His career appeared to be over.

What followed was one of the great parliamentary performances of the century. Palmerston rose a little before ten on a summer night and spoke – without notes – until nearly half-past two in the morning, reviewing in a single sweep his entire European policy since 1830, from the sunny plains of Castile to the mountains of Switzerland, from the rugged Alps into the smiling plains of Lombardy. A panoramic survey of 20 years of history, culminating when he reminded his classically educated audience of the ancient dictum: Civis Romanus sum. As the Roman citizen of antiquity could walk the world confident that the might of Rome stood behind him, so, too, should a British subject know that the strong arm of England  – and crucially, her Royal Navy – would protect him against injustice and wrong. This was the instinctive reach of a mind formed by classical education for the precedent that fused legal right with imperial fact – the kind of reach available to the educated generalist, but closed to the specialist. Palmerston had read his Cicero, and he proposed to his colleagues that they take Rome as their lens for making sense of the world they faced. Lady Palmerston, whose eyes had never left his face, thought the speech had lasted just an hour. It had lasted four hours and 35 minutes.

The point goes beyond rhetoric. Palmerston did not choose between law and interest. He wrapped the assertions of raw power (the fleet) in the language of legal right (civis Romanus sum) and the fusion of the two was what made it work. He understood that British power depended on the claim to act within a framework of right, because that claim was what made smaller states accept British leadership. Strip away the legal scaffolding and you do not produce a more effective foreign policy. You produce what the Athenians understood bitterly after the Melian controversy depicted in Book Five of Thucydides’ History of the Peloponnesian War: a foreign policy that no one wishes to follow.

Consider how Palmerston arrived at this understanding. One of the last true Whigs, he came to the Foreign Office in 1830 having spent 20 years as Secretary at War, a largely administrative position that left him ample time to breed racehorses, conduct love affairs and develop an extraordinarily wide acquaintance with the texture of British society, both at Court and in the St James’ clubs alike. He wrote his own dispatches in prose that could be printed in the newspapers as literary work. He understood commerce, Parliament, the press and the military establishment, and he was himself a militia officer who thought seriously about expeditionary forces and the relationship between naval dominance and diplomatic leverage. Victor Hugo, meeting him at dinner, wrote that Palmerston appartient un peu à l’histoire et beaucoup au roman – ‘belongs a little to history and much to the novel’. This is the character of the remarkable individual in foreign affairs: not the narrow strategic imagination of the doctrinaire, but the strong mind broadly cultivated and capable of holding together what the specialists pull apart: power and law, precedent and circumstance.

The man who succeeded Palmerston from the opposite benches as the grand maître of European diplomacy was an improbable figure. Disraeli is the case for the outsider: the man whose formation has nothing to do with professional requirements of the role and everything to do with the quality of the mind that fills it. Disraeli entered politics with no connections, no university education, no professional qualification of any kind. He had been bankrupt. He had written silver-fork fiction. He had travelled the Ottoman Empire in a state of Byronic self-invention, dining with Albanian beys, smoking with pashas and arriving in Jerusalem thunderstruck. In Disraeli, pose and sincerity were inextricably interwoven; even the sincerest sentiments took on an air of the stage when he spoke.

At the Congress of Berlin in 1878, this quality proved to be the most formidable diplomatic weapon in the room. His extraordinary career and mysterious origins fascinated the entire cosmopolitan world assembled there. Stories of the long-vanished romance of his youth were revived; his novel Henrietta Temple, written in the 1830s, became the rage in fashionable Berlin. He scarcely missed a single reception or dinner, was indefatigable in making the acquaintance of every person who mattered, and never relaxed for a moment in his struggle for British interests. He caused a sensation by addressing the Congress in English – whether by design or by sheer ignorance of French, the effect was the same: a note of British intransigence from the start. A.J.P. Taylor tells us that he allowed it to be known he would break up the Congress if the Russians resisted and ordered – or said he would order – a special train to leave Berlin, the first time this weapon was added to the technique of diplomacy. One of his biographers records a detail that is almost too perfect, perhaps, to be entirely true: Disraeli’s ignorance of military matters was an asset when it came to bluff, for he genuinely believed what he said, and, being convinced himself, he in turn sounded convincing to others.

The Congress produced a settlement that was followed by almost as long a period of European peace as the interval separating the Crimean War from the Congress of Vienna. It was achieved by a novelist’s instinct for character, a theatrical willingness to take risks grounded in a reading of personality rather than merely a strategic assessment, and an outsider’s freedom from the conventions that bound every professional diplomat in the room. Gladstone, his great antagonist, for all his moral seriousness and grinding industry, could never have done it. It required a mind formed by fiction, by failure, by the experience of being an outsider in one’s own country – by everything that a professional career in strategic policy today is designed to exclude.

The other great beast in Berlin was the Iron Chancellor, whom everyone reaches for when they wish to invoke Realpolitik and whom almost everyone misunderstands. The standard version is well-known: blood and iron, the wars of German unification, the subordination of morality to the interests of Prussia, the subjugation of the very Junker elite to which Bismarck himself belonged. But the Bismarck who matters most to us is not the Bismarck of 1866 and 1870. It is the Bismarck of the two decades that followed, decades seldom revisited once the reader has been exhausted by the whirlwinds of unification. This is the man who, having unified Germany by force, spent the rest of his career constructing the most elaborate system of diplomatic restraint that Europe had ever seen.

The Austro-German alliance, the League of the Three Emperors, the Triple Alliance, the alliance with Romania, the Reinsurance Treaty with Russia – this extraordinary web of commitments, some mutually contradictory, all designed to keep France isolated and prevent the nightmare of a two-front war – was not the work of a man who despised rules and norms. Au contraire, it was the work of a man who understood that the assertion of naked power without institutional scaffolding was unsustainable. He had made the new Europe; now he strove to preserve it. He ceased to be Cavour and became Metternich. He, too, became a rock of order.

The Bismarckian system is the best single demonstration of why statecraft cannot be reduced to a single doctrine. It was something of a conjuring trick, a piece of conscious virtuosity. Bismarck scattered promises so as not to carry them out. He promised to fight on the side of Austria-Hungary in order to make her friendly to Russia, and on the side of Italy, securing her neutrality. His two great creations, the League and the Triple Alliance, were at cross purposes with one another: the League an anti-British combination, the Alliance specifically not directed against Britain. He could hold these contradictions in suspension because he possessed a mind of extraordinary range; a Junker who read Shakespeare and Spinoza, who had spent years managing his estates in the political wilderness and developing that feel for the limits of the possible that others later tried to theorise. He understood irony and tragedy as political categories. And he knew when to stop.

When the professionals replaced him, the system collapsed. Leo von Caprivi, his successor as chancellor, knew nothing of foreign affairs. Marschall von Bieberstein, the new secretary of state, not much more. Both relied on Friedrich von Holstein, a permanent official who established a control over Germany’s foreign policy lasting 16 years. He was the archetype of the professional bureaucrat who understood procedures but not the spirit animating them. The Reinsurance Treaty with Russia was allowed to lapse simply because the professionals could not understand what it was for. Within four years, France and Russia were being forced together, whether they liked it or not. The Franco-Russian alliance – the nightmare Bismarck had spent 20 years preventing – came into existence almost immediately after his departure. The strategic realities facing Germany were the same. Yet the mind operating the system had changed, and everything followed from that.

What connects Metternich, Palmerston, Disraeli and Bismarck is the quality of formed personality, the cultivated generalist whose judgement emerged from a breadth of experience that had nothing obviously to do with foreign affairs. Novels, music, philosophy, estate management, the habit of wide and unsystematic reading, the texture of a life lived in many registers. Each brought to the Congress table a formation shaped by domains that bore no direct relation to the questions they would face there.

And there is a further dimension that the contemporary debate has entirely forgotten: the order these men built and maintained was a material system, underwritten by British maritime power, by harbours and dockyards, by the legal framework of belligerent rights and the suppression of privateering, by militia budgets and gunboat fleets, and the relationship between naval dominance and the European balance of power. The historian of seapower Andrew Lambert has shown, in his recent study of British strategic policy after Waterloo, that the statesmen who operated this system understood all of its dimensions simultaneously: diplomatic, military, economic, legal, material. Castlereagh’s most consequential achievement at Vienna was arguably not the territorial settlement but the exclusion of maritime belligerent rights from the agenda. This was a single act that preserved the legal basis of British economic warfare for a century. Palmerston understood expeditionary logistics and the economics of naval deterrence. The Duke of Wellington designed a deployable British force for Belgium on which the entire European settlement depended. The breadth of mind that made their statecraft possible was the essential precondition for comprehending the system as a whole. They understood the law of nations because they understood nations as civilisations with histories, literatures and religions.

The crisis facing British statecraft – and statecraft in general – is real. But it is not the simple question of too much legalism or too little realism, or of the correct formula weighting one against the other. It is a crisis of formation. Beginning from first principles rather than from theoretical abstractions, it requires the retrieval of a political and advisory class capable of the kind of judgement that made order-building possible in the first place – the unashamed polymath, the exceptional individual, the practitioner whose historical sense is integral to analysis, whose authority derives from breadth of cultivation rather than narrowness of expertise. That figure has been driven from public life, and rediscovering their kind is an urgent task. The tradition that needs recovering is one of character: of minds formed by wide reading, by the experience of failure, by immersion in languages and literatures and histories that have no obvious policy application, by the habit of thinking across the very boundaries that the modern university and the think-tank are designed to enforce.

Metternich would have understood this. Palmerston would have laughed at the suggestion that it needed saying. Disraeli would have written a novel about it. Bismarck would have poured himself a glass of something strong and observed that the English have a peculiar genius for stating the obvious as though it were a revelation.

They would all, however, have agreed on one thing: that statecraft is not a profession. It is a vocation, and like all vocations it demands a formation that cannot be reduced to academic credentials or a curriculum vitae.