The result of Sunday's referendum came as a surprise to most, in particular the margin of victory for the "No" campaign and Mr. Tsipras. A new day begins today for the Greek nation, and with it very great challenges.

I believe Mr. Tsipras will have to be prepared to engage in serious negotiations if he wants to win back the credibility that he has lost in recent weeks.

I think the Greek people - both those who voted "Yes" and those who voted "No" - are expecting positive results from these negotiations. This is Mr. Tsipras' historic duty.

My generation went through very difficult times, including civil war and deep divisions. I therefore hope that the discord that exists between the "Yes" and "No" camps can be overcome. Greece's European friends and partners should also help here - and must play a reconciliatory and productive role for a member state of the EU and the Eurozone that deserves a better future.

I am moved by this opportunity to have my words published by DW, 40 years after its presence in Greece made it the most important European broadcaster, when it gave Greeks the knowledge and courage with which to fight dictatorship.

I can still remember the DW team from back then, some of whom are no longer with us. With a heavy heart, I think of them today. It is my conviction that we have remained true to the values for which we fought back then, to democracy and our pro-European path.

Karolos Papoulias was president of Greece from 2005 to 2015. He also served two terms as Minister for Foreign Affairs.