I still hope that the American system of checks and balances will ultimately prevent this man, Donald Trump, with his erratic political style, from jeopardizing our European security architecture.

The construction of social housing and the attempt to support families seeking to buy their own homes are all projects from the 1960s and '70s. It all sounds old-fashioned, but it is actually completely modern.

It became obvious that we had completely failed to impose rules on unbridled speculative capitalism. That destroyed financial systems, hollowed out state systems and deeply shook German social stability. Can you recall the debate about "locust" hedge funds - even if it's a terrible term. The speculator capitalists roamed the land, stealing the substance from companies and throwing away the shells. And we were powerless.

I know people's problems: the problems of those who work hard, who must slave away. The couples who have two incomes but who can nevertheless barely cover their rent. The people who get stuck in traffic on their way to work. The people who have to wait in vain for a train to come just as they are supposed to be picking up their children from daycare. I can say with a clear conscience to those people: I understand your problems. And I will do all I can to decrease them.

For me, respect is an extremely important political term. Since I began campaigning, it has been at the heart of each of my speeches. Many people have the feeling that politicians aren't paying a sufficient amount of attention to them. And then, when the refugees arrived on top of all problems, there was a feeling: You do everything for them, but nothing for us. This mixture of frustration and fear has led to this reaction. That is why it is so important to show these people: We respect you.

I would have oriented myself in case of Donald Trump according to what former German Chancellor Gerhard Schröder said to then - U.S. President George W. Bush when the Americans launched a war that was in violation of international law. Schröder showed that a German chancellor can act in a clear and self-confident manner toward a U.S. president.

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.