Washington CNN  — 

German Chancellor Angela Merkel urged Harvard graduates Thursday to “tear down walls of ignorance and narrow-mindedness” in a speech that was an apparent rebuke of President Donald Trump’s policies and worldview.

In her commencement address at the university, Merkel warned against the perils of isolationism and nationalism, pushed for action on climate change and said to never “describe lies as truth and truth as lies.”

The Chancellor spoke in German and used a translator, but notably switched to English to close out her speech and said, “Tear down walls of ignorance and narrow-mindedness, for nothing has to stay as it is.”

Merkel, who grew up in Soviet-controlled East Germany, said the tearing down of the Berlin Wall almost 30 years ago had allowed her to start her political career.

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Walls exist “in people’s minds” and “between family members, as well as between groups within the society, between people of different skin colors, nations and religions,” she said.

But, Merkel said, “walls can collapse.”

“Dictatorships can disappear,” she continued. “We can halt global warming. We can eradicate starvation. We can eliminate diseases. We can give people, especially girls, access to education. We can fight the causes of displacement and forced migration. We can do all of that.”

The Chancellor, who never mentioned Trump by name, called for “truthfulness in our attitude toward others” and ourselves, which she said “requires us not to describe lies as truth and truth as lies” – a line that was met with a standing ovation.

Merkel underscored the importance of multilateral, global actions and working “together rather than alone.”

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She cautioned against protectionism and trade conflicts, which “jeopardize free international trade, and thus the very foundations of our prosperity,” an apparent reference to Trump’s trade war with China.

Merkel urged the graduates to “view the world in the eyes of others,” and not make snap decisions. She said, “Don’t always act on our first impulses, even when there is pressure to make a snap decision, but instead take a moment to stop, be still, think, pause.”

The Chancellor warned, “Nothing can be taken for granted. Our individual liberties are not givens. Democracy is not something we can take for granted. Neither is peace, and neither is prosperity.”

“But if we break down the walls that hem us in,” Merkel said, “if we step out into the open and have the courage to embrace new beginnings, everything is possible.”