After all the criticism and ridicule heaped on the European Union over the fiasco of its quotas on Chinese textiles imports, it is time to speak up in its defence. Perversely and unwittingly, it has done the cause of free trade a favour by showing up the manifest absurdity of the alternative.

The economic benefits of open markets, although real, are hard to quantify precisely because they are long term and widely spread. But the costs of trade protection, for its practitioners as well as its targets, are easier to identify. Seldom have they been exposed with more brutal clarity than since the EU sealed the deal, amid much self-congratulation, in June.