The Bourbons remain true to Talleyrand’s bon mot: they learn nothing, and forget nothing.

King Felipe VI’s fateful speech on Tuesday night prepares the way for full-blown intervention to crush the Catalan insurrection by any means necessary, with the unqualified backing of a European Union that has lost its moral compass.

The rebel leader Carles Puigdemont said King Felipe was “pouring petrol on the fire”. The Catalan riposte is tragically predictable. Its parliament will declare unilateral independence from Spain on Monday unless the Catholic Church can mediate an eleventh-hour compromise.

As matters stand, the Catalans are embarked on a course that will lead to their expulsion from the euro and the closure of their economic borders, for that is what the Spanish government has vowed to do – what the EU has endorsed, thinking that its dangerous bluff will never be called.

The Jesuitical casuistry of the Commission is revealing. I was The Daily Telegraph’s EU correspondent in early 2000 when Brussels imposed sanctions against Austria merely for admitting the right-wing Freedom Party into its governing coalition.

The party had not broken any laws. It was legitimately elected. The matter was an internal Austrian affair. It was clear to many of us covering the episode that much of the animus against the Freedom Party stemmed from its Eurosceptic insolence.

We have seen a pattern of asymmetry in the way Brussels intrudes into the internal affairs of member states. It has repeatedly berated – and threatened – the eurosceptic governments of Poland and Hungary over the rule of law. “The double standard of the Commission leaps to the eye,” said Polish MEP Ryszard Legutko.

Frans Timmermans, the Commission’s vice-president, crossed the Rubicon by backing the actions of Guardia Civil on Sunday. Speaking in the European Parliament in a carefully-scripted message, he endorsed a decision to storm voting centres and to bludgeon Catalan citizens who were trying to vote – rightly or wrongly, but peacefully and in good faith.

“None of us want to see violence in our societies. However it is a duty for any government to uphold the law, and this sometimes does require the proportionate use of force,” he said.

Frans Timmermans, the Commission's vice-president, said the measures used to storm voting centres in Catalonia were 'proportionate'

This comment is Orwellian. The actions were patently not proportionate. There was no need to use any force. The vote could simply have been declared null and void.

The violence almost certainly breaches multiple clauses of the EU's Charter of Fundamental Rights but as I always feared would happen, the EU uses the Charter selectively, when it serves the interests of the European Project. Be that as it may, Brussels now bears a high share of responsibility for what happens next in Spain. If its iron-fist apologia for violence causes the country to spin into insurgency and counter-insurgency, the EU owns the outcome.

Spain’s authorities and media talk about the crisis as if it were chiefly a financial disaster for Catalonia, one that could be isolated. Much inks has been spilt on a Credit Suisse report warning of a 20pc crash in output – for the Catalans. Finance minister Luis de Guindos says the secessionist state would suffer “brutal pauperisation”, a collapse in GDP of 25pc to 30pc, and a devaluation of up to 50pc. Spain would miraculously come through just fine.

To the extent that Spain’s governing elites believe this fairy tale, they are less likely to recoil from catastrophic error. Former vice-president Alfonso Guerra (a Socialist) is already calling for the army to put down the Catalan “coup d’etat”.

Markets are struggling to navigate these complexities. Investors are fleeing Catalan debt, driving up yields on 2018 bonds threefold since late June to 2.6pc, but yields on equivalent Spanish bonds have scarcely moved.

The IBEX index of equities fell 2.4pc on Wednesday in the worst drop since Brexit. Yet much of the damage has been for Catalan lenders Sabadell and Caixabank, on fears that they could lose access to ECB liquidity. Oryzon Genomic leapt 27pc after announcing that it would relocate from Barcelona to Madrid.

This all plays to the comforting narrative that economic dangers are largely confined to the rebels. This is self-evidently absurd. Catalonia makes of a fifth of Spanish GDP. It is a hub of dynamism with a per capita income higher than the EU average. It is structural net contributor to the Spanish treasury, even though its finances are a mess.

If Catalonia were quarantined and reduced to ‘brutal pauperisation’ as Mr de Guindos suggests, Spain itself would slide towards bankruptcy. Its public debt ratio would jump instantly to 120pc of GDP. The economy would collapse into a pan-Iberian depression. The budget deficit would jump to double-digit levels. Those Spanish banks holding €215bn (£190bn) of Spanish public debt would be engulfed by our old friend the 'doom-loop'.

It would be impossible for the ECB to shore up the system through QE alone. The only way to avoid a Spanish default would be to activate the bail-out mechanism (OMT), but this would entail tough terms and a vote in the German Bundestag. By then, a fresh eurozone crisis would be raging.

We all now watch with horror as events unfold. One of the constitutional functions of the Spanish monarchy is to act as national arbiter. King Felipe has instead asserted himself as champion of the hardliners, denouncing the Catalan leaders as Putschists, guilty of “inadmissible disloyalty”, “totally beyond the boundaries of the law and democracy”.

Barcelona’s mayor Ida Colau, who opposes secession, said the speech was “irresponsible and unworthy of a head of state ... There was no solution. No mention of the wounded. No call for dialogue.”

On the surface of it, King Felipe is of course correct to declare it the duty of the state to uphold the “constitutional order” and to protect the rights of law-abiding Catalans being dragged against their will into a desperate adventure.

The trouble with this rhetoric – and there has been a concerted attempt in Madrid to ridicule last Sunday’s vote as “farce”, a non-event – is that it willfully ignores the volcanic strength of Catalan feeling.

It should be obvious that matters have moved beyond "farce". Whether you blame the headstrong Catalan leaders for charging ahead or blame the guerrilla campaign by Spain’s Partido Popular to roll back Catalonia's devolution settlement, the fact is that 2.26m Catalans voted (and many more tried), with 90pc backing secession.

Catalan police chief Josep Lluis Trapero faces sedition charges for refusing to join assault on voters

The eruption of national feeling is a political fact. Common sense would suggest that the only way in a modern democracy is a legal referendum as in Scotland, or a negotiated deal along the lines of Basque autonomy with full tax-raising powers.

Yes, the Catalans leaders are in breach of Spain’s constitution but elemental questions of national identity are always political. At a certain point it becomes an evasion to fall back on legalisms. Courts and constitutions are by nature the tools of the status quo, and constitutions can in any case be changed. Indeed, Spain's constitution was changed on the orders of the ECB conveyed in a secret letter to former premier Jose Luis Zapatero.

The repression of 2017 has begun. The police chiefs of Catalonia's Mossos d'Esquadra are already charged with sedition. Madrid is preparing to launch direct rule and a campaign of coercion. Brussels has given a green light and is totally complicit. Welcome to the Europe’s brave new world.