Having a place to live is a fundamental right and the state must establish a framework that ensures that apartments are affordable.

I have friends in politics who really put the friendship to the test through their behavior.

We are in the middle of a tough, ideological conflict that is being waged across the entire continent. On the one side are those who say that global challenges like migration and terror cannot be met with national parochialism. On the other side are those who would like to see a renaissance of the nation-state.

Germany is not a fair country. Millions of people believe that things aren't fair in this country. Company profits and bonus payments have increased at the same rate as precarious employment situations.

Donald Trump has made the principle of purposely breaking a taboo into a means of achieving his political objectives, which is something that he has in common with Turkish President Recep Tayyip Erdogan and Hungarian Prime Minister Viktor Orbán. Trump systematically violates international rules. But we cannot allow ourselves to forget that Trump is not the U.S.

Solidarity is the fundamental idea of European cooperation. If a country feels itself to be militarily threatened and calls for soldiers, weapons and sanctions, then that's what it gets. When governments say they need money from the structural funds to stabilize their economy, that's what they get. But you can't cherry pick solidarity.

There are certain reactions that you aren't allowed to show in Berlin, for example that you feel offended. If you do, the best-case scenario is a sympathetic article along the lines of: Nice guy, but he's not up to it. The alternative is to don a suit of armor and become cynical. But that's not healthy either: Cynicism is the worst characteristic a politician can have. That's why you have to have an internal balance in Berlin, so you can stay true to yourself. And I have that.