Thirty years have passed since the collapse of the Berlin Wall, which divided Germany into East and West and symbolized the Cold War.
Freedom and democracy have spread through Eastern Europe, but it is worrisome that new exclusionist moves that could lead to new divisions have emerged.
In 1961 East Germany began to build the Berlin Wall stretching a total of about 155 kilometers to prevent citizens of East and West Berlin from traveling between the two areas.
Berlin, in which the same ethnic group was split between capitalist and socialist systems, was the frontline of the Cold War between the United States and the now-defunct Soviet Union.
Citizen power eventually broke down the iron curtain. People across the world were excited to see many citizens climb up the wall and use picks to break it. With the Western bloc's victory, many people even foresaw an end to the history of confrontation.
Two politicians -- German Chancellor Angela Merkel and Hungarian Prime Minister Viktor Orban -- have embodied the modern history of Europe.
Merkel spent her childhood in East Germany and became a physicist. On the occasion of the fall of the Berlin Wall, she joined a citizens' political party and began her political career. She says the importance of freedom remains deeply etched in her mind.
She has placed emphasis on a liberal sense of values and confronted difficulties facing Europe. She made great achievements in dealing with the euro crisis and opened the door widely to a flood of refugees in Europe in 2015.
However, the recent spread of exclusionist trends is worrisome. Populist political forces are gaining support from those dissatisfied with globalization and the European Union.
Prime Minister Orban is a typical example. He was an activist who called for the immediate withdrawal of Soviet forces from Hungary under the socialist regime in the Cold War period. However, the reformist politician is now pushing an anti-immigrant policy.
He has warned that European culture rooted in Christianity could be threatened by immigrants, most of whom are Muslims, and constructed a fence along its border with Serbia to prevent refugees and immigrants from crossing into Hungary.
Since 1990, some 1,000 kilometers of fences to prevent refugees and immigrants from crossing national borders have reportedly been built in Europe, roughly six times the length of the Berlin Wall.
Europe has come to the crossroads. A "free and open Europe" that Merkel is pursuing has come under mounting criticism and appears to be threatened by Orban's exclusionist policy.
The EU's motto is "United in diversity." Now is the time for European citizens to humbly listen to Merkel's call to "tear down walls of ignorance and narrow-mindedness." New walls that alienate people must not be built.