The British chemist, Sir Humphry Davy (born 1778), liked dangerous experiments. He was fired from his job as an apothecary for causing constant explosions. Later, as a chemist, he enjoyed inhaling the gases he worked with. This helped him discover that nitrous oxide (laughing gas) was a potent anaesthetic. "Unfortunately," notes a short guide to his career from Oxford University Press, "the same habit led him to nearly kill himself on many occasions and the frequent poisonings left him an invalid for the last two decades of his life."

It was probably worth it: Davy isolated substances including calcium and strontium, identified the element iodine and made the first electric light.

Much like Davy, Britain is now experimenting on itself for the benefit of humanity. Advanced societies rarely do anything so reckless, which is why the Brexit experiment is so valuable. In between self-poisonings, Brexit keeps producing discoveries that surprise both Leavers and Remainers.

Here are some early lessons for other countries.

WHEN YOU FOCUS ON A WEDGE ISSUE, YOU DIVIDE SOCIETY

The Brexit vote has introduced unprecedented rancour into a traditionally apolitical country. Insults such as "enemies of the people", "saboteurs", "racists" and "go home to where you came from" are now daily British fare.

Brexit rows split generations at family weddings and Christmas. All this was avoidable: Until the referendum, few Britons had strong views on the European Union, just as few Americans thought about transgender bathroom habits until their politicians discovered the issue.

If you have to address wedge issues, best to aim for compromise rather than a winner-takes-all solution such as a referendum.

ALL COUNTRIES NEED REAL-TIME ELECTION REGULATORS

There have always been people who lied to win votes. But now they have social media. Every slow, understaffed 20th century election regulator must therefore retool itself into a kind of courtroom judge who can call out falsehoods instantly. The model is the UK Statistics Authority's reprimand of Foreign Secretary Boris Johnson last Sunday, after he repeated the nonsense that leaving the EU would free up £350 million (S$635 million) a week for the National Health Service.

REVOLUTIONARIES INVARIABLY UNDERESTIMATE TRANSITION COSTS

Maybe if you have a blank slate, being out of the EU is better than being in it. But the calculation changes once you have been in the EU for 43 years. All your arrangements are then predicated on being in, and suddenly they become redundant. The cost of change is a classic conservative insight, though it's been forgotten by the Conservative Party.

ALMOST EVERY SYSTEM IS MORE COMPLEX THAN IT LOOKS

Most people can't describe the workings of a toilet, writes Dr Steven Sloman, a cognitive scientist at Brown University. The EU is even more complicated, and so leaving it has countless unforeseen ramifications.

Most Britons had no idea last year that voting Leave could mean closing the Irish border, or giving ministers dictatorial powers to rewrite law. Because of complexity, so-called common sense is a bad guide to policymaking. Complexity is also an argument against direct democracy.

IMMIGRANTS FULFIL A ROLE

Any society in which they live comes to depend on them. Britain's NHS and the City of London would buckle without them. You may calculate that your distaste for immigrants is worth some lost functioning, but you have to acknowledge the trade-off.

You have to choose who to surrender your sovereignty to. Brexiters are right to say that the EU has usurped some British sovereignty. But as former prime minister John Major remarks, in a connected world the only fully sovereign state is North Korea.

All other countries are forever trading away bits of sovereignty. For instance, the trade deal that Britain hopes to sign one day with the EU will entail adopting the EU's standards on everything from cars to toys. You can decide to give away your sovereignty in new ways but, in practice, you can't decide to keep it.

A GOVERNMENT CAN HANDLE ONLY ONE MASSIVE PROJECT AT A TIME

This is at best, and only if the whole government agrees on it. There simply isn't the staff or head space to do much more. Carrying out Brexit means not fixing what Mr Johnson in February last year called "the real problems of this country - low skills, low social mobility, low investment, etc - that have nothing to do with Europe".

NEGOTIATIONS GET HARDER WHEN YOU LOSE YOUR COUNTER-PARTY'S TRUST

That's what Greece discovered during its negotiations with the EU, says Greek economic analyst Paris Mantzavras of Pantelakis Securities. Mocking the other side in public - as former Greek finance minister Yanis Varoufakis did, and as British politicians now do regularly - is therefore a losing tactic.

THERE IS NO RESET BUTTON IN HUMAN AFFAIRS

Britain cannot return to its imagined pre-EU idyll because the world has changed since 1973. Nor can Britons simply discard the Brexit experiment if it goes wrong and revert to June 22 last year. The past is over, so it's a poor guide to policymaking.

These lessons come too late for Britain itself, so please consider them our selfless gift to the world, like football.

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