We need a big debate in society about how we are going to shape Europe and tame capitalism. A government must provide direction and make concrete proposals. It is one of Angela Merkel's biggest failings that she doesn't do this.

We are seeing now that without the contribution of the Social Democrats, Germany cannot be governed. We are a proud and self-confident party. We should now act based on that pride, and not out of fear.

We all have to accept accusations that we ignored the refugee crisis for far too long. The first time that I referred to the Mediterranean Sea as Europe's cemetery was in October 2013, when hundreds of people drowned off Lampedusa. Italians, Maltese, Greeks and Spaniards have been pleading for help for years. But nobody cared.

I'm not a populist. But I try to present complicated issues in such a way that people know where I stand.

I'm fully aware that my vision of a European bicameral parliament can't be implemented tomorrow. I'm also not an integration fanatic.

It's not attractive at the moment to vouch for the European idea. I still do it, because I believe nothing would be better for our continent.

Businesses will only invest in Greece if three conditions are fulfilled. First, there must be a clear commitment to the euro. No businesses will invest if they have to fear that Greece will leave the euro zone at some point. Second, the Greek government must be prepared to work together with European institutions in order to restructure the country.