Britain is coming to a fateful decision for itself this week, and possibly for the world. The question of whether Britain's interests are best served by remaining in the European Union or leaving it has been debated to exhaustion in that country. Much less has been said about the wider consequences of a Brexit.
What will it mean for a world economy still fragile since the financial crisis eight years ago? The EU ranks with the United States, China and Japan as one of economic superpowers. If the British vote to leave, currency and stock markets will register the shock of business and investment advisers at the greater uncertainty that comes into their calculations. No member has left the EU since it came into existence more than 50 years ago. If Britain goes, others could follow. Polls already find opposition to the EU in France is even higher than in Britain, and France was a foundation member of the community. It and West Germany, as it was, were the pillars of Europe's resolve not to repeat the wars that engulfed the world twice in the 20th century.
The "remain" advocates in Britain have done themselves no favours by dark reminders of the wars. It is hard to imagine western rivalries coming to blows again if the EU was to disintegrate. The Cold War changed their security environment and the greater concern now is that a weakening of the EU could have dire implications for some of its members who have escaped Russian dominance since the collapse of the Soviet Union. The Baltic states are probably more nervous than they want to say at the possible consequences of Britain's vote.
Strictly speaking it is Nato, not the EU, that provides Eastern Europe with security from Vladimir Putin's strategic ambitions for Russia. But having seen Nato's caution when Crimea was taken and Ukraine destabilised, Mr Putin could be further encouraged by any weakening of the economic glue that binds eastern Europe to the Atlantic alliance. The United States has made that concern clear.
Britain has been Washington's most loyal ally in Europe and that will not change if Britain leaves the EU, but Britain will change. If Britain votes to leave, Scotland is just about certain to leave the United Kingdom. Many Scots hold their membership of Europe in higher regard than their membership of Britain. In the event of Brexit they would demand yet another referendum on Scottish independence and would very likely get the result they have long desired.