The membership survey was a great moment for inner-party democracy. We can't go back, nor do we want to. Our members are pouring their hearts into this campaign. But people don't join the Social Democrats party just to put up posters. They join because they want to help steer the party.

One of the richest and largest markets in the world, Europe can set global standards. And if a French president is prepared to at least consider clear rules in the Eurozone, then it would be fatal if Germany were not to react.

In political life, it is extremely difficult to remain loyal to a friendship when constellations of power or interests are in the way.

There are surely people in London who would love to play us off against each other. That would be disastrous for the EU.

Just come to Brussels after a Council meeting. Do you know what happens? Every head of government holds his or her own press conference. They all say the same thing, in 24 languages: I was able to push through my agenda. And if the result is anything other than what they desired, the message is: Brussels is to blame. It has been this way for over 20 years. These messages stick with people, and that's deadly for Europe.

You can't always be demanding solidarity from others and then refuse to show it yourself.

We're at a historical juncture: A growing number of people are declaring what has been achieved over the past decades in Europe to be wrong. They want to return to the nation-state. Sometimes there is even a blood and soil rhetoric that for me is starkly reminiscent of the interwar years of the past century, whose demons we are still all too familiar with.