By leaving us, you are making us sadder, poorer and more prone to the errors that made so many of you vote for Brexit. The only solace I take from your departure is the thought that Brexit will convince you that a European Union should be invented even if it did not exist. And that it will convince us, on the Continent, to democratise properly the one we have so as to serve our people’s needs and, yes, to lure you back as well.