No one knows how long the far-reaching British Empire lasted: Perhaps 350 years or much longer. Now, just a part of a European union, many are uncertain about reasons cited to leave it. For example, it is a mystery just how many United Kingdom laws come from Brussels: Somewhere between 15 and 55 per cent, it seems. And no one is sure if a "Brexit" will break it - a possibility if pro-euro Scots use the outcome to push for independence. Some clarity might emerge after the referendum, on whether Britain should remain in the EU, to be held on June 23. But for the moment, the date is the only thing one can be sure about.
What a difference a year has made for British Prime Minister David Cameron. Early last year, there was only a remote chance of a popular vote for Brexit. Now, he is battling even his own party to support renegotiated terms of Britain's membership, as pollsters (whom no can be sure of, after getting last year's election results wrong) say public opinion is teetering on a knife-edge. It has proved to be a risky gamble for Mr Cameron, who had made the referendum an election pledge.
The altogether messy state of affairs has made others flinch too, especially after sterling's plunge rattled currency markets and the Czech prime minister said his own country might debate EU membership if a Brexit takes place. Three-fifths of his countrymen are reportedly disillusioned by the EU. Uncertainty about Europe's future is something the world would prefer to avoid as it would undermine economic confidence, security and stability. It would also do no one any good to have a disoriented Britain lurching on the sidelines, if Brexit comes to pass.
There is no doubt EU membership is costly, the single currency is problematic to some, migration is a prickly issue, and certain Euro policies are said to be dysfunctional. But on the flip side, the EU has rationalised a hotchpotch of rules in Europe; created a single market within which goods, capital and people can move freely; given members a stronger voice globally; and helped to make another war in Europe unthinkable.
Like many of his countrymen, Mr Cameron was chary of the EU's push for "ever closer union", unhappy about social benefits for EU migrants, fearful about EU legislation that can't be blocked nationally, and insistent about getting a fair shake if the UK remains out of the euro zone. But many of his countrymen brush aside the concessions offered by the EU as they are convinced Britain can do a lot better on its own. Brexit will free small and medium-sized enterprises from the deadweight of EU regulations. It can reclaim its territorial fishing waters, create a more vibrant market, and turn London into a "freewheeling hub for emerging-market finance - a sort of Singapore on steroids", as the Economist magazine put it. It is an alluring vision. The trouble is no one can be sure about anything.